“There Can Be No Agreement to Take up Arms against the Turks Unless We First Restore the Empire”: The Fall of Constantinople and the Rise of a New Political Dynamic in the Holy Roman Empire, 1453–1467

Abstract

While the Europe-wide cultural impact of the fall of Constantinople to Sultan Mehmed II is well known, its political reverberations in the Holy Roman Empire have received comparatively little attention. This article argues that the events of 1453 inaugurated a new dynamic in the empire that facilitated the polity's consolidation and the creation of new collective institutions within it long before Maximilian I (1486–1519), whose reign is often presented as a constitutional turning point. Some prince-electors had been calling for more effective peace-keeping and judicial institutions for decades before 1453 but lacked the leverage to compel kings and emperors of the Romans to accept political change on their terms. The fall of Constantinople provided a focal point for these negotiations: in return for promising to support an anti-Ottoman crusade, the reformists were able to force a compromise on new peace-keeping legislation at the diets of the 1450s and 1460s. This compromise was catalyzed by public pressure. There was a widely held expectation that leading imperial protagonists should fulfill this mission to defend Christendom, manifested in orations, diplomatic missives, poetry and songs, plays, and early printed pamphlets produced within and for a range of German-speaking public spheres.

Introduction

The conquest of Constantinople by Sultan Mehmed II in May 1453 has long been regarded as a historical inflection point. Its immediate cultural impact, not least via the new literary genre (termed Turcica) in which Latin Christians fixated on the Turks¹ with a combination of sensationalist fear and exoticizing curiosity, is well known,² as is the fifteenth-century papacy's instrumentalization of the issue.³ Rather less attention has been paid to the fall of Constantinople's effects on the internal politics of the Holy Roman Empire. In reaction to news of the event, and in collaboration with papal legates, Emperor Frederick III (r. 1440–93) convoked three imperial assemblies in quick succession in 1454–55—in Regensburg, Frankfurt, and Wiener Neustadt—where he promoted a German-led crusade against the Ottomans.⁴ A rhetorical commitment to repelling the Turkish threat pervaded the preambles of ordinances and recesses issued at imperial diets for the remainder of the fifteenth century⁵ and into the sixteenth, coinciding with a partial institutionalization of the Holy Roman Empire that has often been termed “imperial reform” (Reichsreform).⁶ Yet the “Turkish diets” of the 1450s and the longer-term insistence on crusading against the Ottomans as a raison d’être for the empire barely receive passing mention in the major political narratives of late medieval German history.⁷ For Peter Moraw, the institutionalization of the empire began only after 1470, and he noted the Turks only once in his authoritative political account: as the least threatening among a list of external powers, led by France, whose “pressure” (Druck) catalyzed imperial consolidation.⁸ Hartmut Boockmann, Heinrich Dormeier, and Malte Prietzel have acknowledged the sudden rise in the salience of the Turkish threat in the wake of 1453 more overtly, but questioned the import of what took place in the empire in the immediately ensuing years, as conveyed by such section headings as “Vain strivings for reforms and an anti-Turkish war.”⁹

It is easy to see why historians have been skeptical of or uninterested in the significance of the anti-Turkish crusading rhetoric that came to dominate the sources in the 1450s and thereafter. For all the energy expended on preaching and indulgence campaigns, discussions and orations at diets, and even plans (Anschläge) for collective crusading armies, the members of the Holy Roman Empire conspicuously failed to launch an actual military expedition against the Turks.¹⁰ While the discourses about defending the empire and Habsburg lands against the Turks have been analyzed rigorously,¹¹ it is not immediately clear how these can be linked to conventional accounts of German constitutional history. Why devote attention to such seemingly quixotic, if not outright anachronistic activities, which seem largely irrelevant to the real stuff of the empire's internal institutional consolidation: reforms to what historians tend to call the “imperial constitution” (Reichsverfassung)?

Furthermore, the middle years of the fifteenth century appear to constitute a nadir in the late medieval German lands' long history of internal conflict and violent disorder.¹² Thomas Brady, Jr. has dubbed them “the terrible decades.”¹³ The “Margravial War” (Markgrafenkrieg) of 1449–50 and its acrimonious aftermath; the rivalries between Frederick III, his brother Albrecht VI (d. 1463), and supporters of his cousin Ladislaus Posthumous (d. 1457) in the Habsburg lands;¹⁴ the “Princes’ War” (Fürstenkrieg) that opposed shifting Wittelsbach- and Hohenzollern-led coalitions in Franconia, Swabia, and Bavaria and along the Rhine between 1458 and 1463; and myriad smaller-scale feuds—all contributed to widespread devastation and insecurity across Upper Germany.¹⁵ The 1450s and 1460s saw the penning of increasingly insistent calls for the restoration of order in the empire and German nation, using the traditional language of regional peace-keeping (Landfrieden) while imagining more consolidated judicial and military mechanisms. Yet, as Moraw's authoritative narrative goes, meaningful change would have to await the last decades of the century. Not only did the post-1453 years in the empire fail to yield any German-led crusades, but they seem to many historians to have been fruitless on the practical “reform” front, too.

Without denying that the most substantial institutional reforms did indeed take place at the end of the fifteenth century, this article challenges the prevailing view that the crusading and reformist initiatives in the empire that followed in the wake of the fall of Constantinople were futile or had little significant impact. Its central contention is that—on the contrary—the developments of this period formed an essential precondition to the celebrated changes of the late fifteenth century, namely the mooting of new institutions (the perpetual public peace, imperial cameral court, imperial circles, and Reichsregiment) at the end of Frederick III's reign and their implementation under Maximilian I (r. 1486–1519).¹⁶ While the 1450s and 1460s may not have yielded such concrete results, they saw the establishment of a new political dynamic in the empire by imposing a permanent mission on its denizens—an anti-Ottoman crusade—for which internal reform could be presented repeatedly as an essential precondition.

Discussions about the need for better governance in the empire long predated 1453. For centuries, a Latin and vernacular discourse of imperial and regional peace-keeping—(Land-)frieden—flourished as a legitimizing tool for a range of initiatives and formations, from constitutiones pacis under the Staufer emperors to myriad regional leagues.¹⁷ Demands for governmental reform in the Landfrieden tradition reached a fever pitch under Emperor Sigismund (r. 1410–37) and Albert II (r. 1437–39), typically in connection with calls for a simultaneous reformatio of the Church at the councils of Constance and Basel.¹⁸ However, these proposals remained largely in the realm of prophetic and canonistic treatises (including, most famously, the Reformatio Sigismundi of 1439),¹⁹ or appeared in letters and draft ordinances that were circulated at imperial diets by princely envoys without leading to concrete outcomes. Notwithstanding occasional modest steps in that direction—an ineffective temporary decree to end feuds in 1431, some aspirational regulations in the “royal reformation” (königliche Reformation) of 1442²⁰—the diets of the first half of the fifteenth century had little effect on the institutions of justice and peace-keeping in the empire as a whole. While the political assemblies of this period were gradually coming to be seen as meetings pertaining to a large and diverse community of members (Glieder) of the empire, indicated by the shift in nomenclature for an assembly from curia/hof to dieta/tag, they remained dependent on kings and emperors for their legitimacy and operation, at a time when these rulers were often far from the German heartlands.²¹ For all their voluminous complaints, princes and cities had few means of systematically forcing “reformist” proposals onto the political agenda, and lacked positive justifications for doing so.

The advent of the Ottoman threat as a permanent, universally acknowledged constant in imperial politics changed that. From the “Turkish diets” of 1454–55 onward, all participants at imperial assemblies were expected to frame their agendas as ultimately serving the end of driving back the Turks on behalf of Christendom. Princes and their envoys at the imperial diets who hoped to persuade the emperor and fellow delegates to adopt their proposals on the domestic front presented them as adjuncts and necessary prerequisites to this defensive objective. Put more cynically, “reformists” could use the desperate requests of the papacy and imperial monarchy for action against the Turks as leverage to demand institutional change. Thus, the notional protection of Christendom against the Ottomans became inextricably bound up with projects to reform or restore peace and justice in the empire. The eventual implementation of some of these projects in the last decades of the fifteenth century was an enduring legacy of the dramatically heightened salience of the Turkish threat in the culture and political discourse of the 1450s and 1460s in the German lands.

To understand how this shift in the political dynamic arose in connection with the fall of Constantinople, we must first clarify what exactly it means to speak of “imperial reform”: how did fifteenth-century protagonists articulate the visions of improved governance in the Holy Roman Empire that rose to the fore after 1453? We will also need to examine how and why the perceived threat from the Turks became a normative stimulus for action, as actors across political and social divides, seemingly quite far down the social scale, expressed a close interest in the Ottomans, pressuring leading protagonists to link their agendas to crusading projects and creating an opening for the consistent negotiations over imperial reform. It will then be possible to proceed to a contextualized overview of the political debates and maneuvers of the 1450s and 1460s through which this new dynamic of intertwined “reform” and “Turkish crusade” initiatives played out, culminating in the Landfrieden of 1467: a peace-ordinance negotiated by the emperor and princes that would serve as the blueprint for the new institutions of Maximilian's reign.

“Peace,” “Justice,” and “Order”: A Normative Yet Malleable Semantic Field

When it was published in 1921, Erich Molitor's account of “the strivings for imperial reform until the death of Frederick III” was the first detailed attempt to interpret the dizzying sequence of events in fifteenth-century imperial politics.²² Molitor understood Reichsreform as the quest for “a unitary form of statehood” in Germany, which he argued was partially successful.²³ Six decades later, Heinz Angermeier pursued a similar, if subtler, approach in his magisterial history of imperial reform, arguing that the term captures a long-term dialectical struggle between top-down efforts for the consolidation of royal power and the imperial estates' own increasingly insistent demands for institutionalization on their terms.²⁴ This use of Reichsreform qua constitutional consolidation persists today, though it is often restricted to a shorter chronology, centered on the banning of feuds in the 1495 perpetual public peace and its accompanying “reformist” judicial apparatus.²⁵

However, a crescendo of skepticism about Reichsreform has developed in parallel. Replying above all to Angermeier, Peter Moraw argued in 1987 that the concept was anachronistic, requiring notions of statehood and a political bloc of “estates” that barely existed for most of the fifteenth century. Instead, Moraw favored characterizing the accelerating contact and consolidation in the empire after 1470 as “the reconfiguration [Umgestaltung] of the imperial constitution.”²⁶ Studies of the practical operation of the empire, such as Ralf Mitsch's analysis of networks of imperial commissioners who sought to enforce Frederick III's mandates, have shown that there was a large gulf between rhetoric about urgent political change and the modest (though not entirely nonexistent) means for implementing such change.²⁷ From another perspective, Claudia Märtl has noted the heterogeneity of authorship, content, and audience among the so-called Reformschriften which form the main focus of older accounts of imperial reform, throwing the very coherence of the concept into question.²⁸ For good reason, then, some historians now place the term “Reichsreform” in quotation marks.²⁹ Yet, perhaps because it so usefully captures an ongoing series of thematically similar conversations about (even if not actual implementations of) governance in the empire, few have followed Moraw in abandoning it entirely.

One productive way forward is to recognize that a cluster of broad concepts and discourses centered on issues of governance can clearly be detected in the sources, while acknowledging that this in itself is not evidence for a consensual notion of what “reforming” the empire meant, and that the authors of these sources could have widely diverging social and political backgrounds and interests. In other words, “imperial reform” can be thought of as a semantic field, consisting of discursive motifs about reform and restoration that many political actors could deploy without having to use one specific concept or to share a concrete agenda. For one thing, this helps us to sidestep a terminological incongruity: only a minority of sources that relate to improving governance in the Holy Roman Empire use the term reformatio/Reformation and its corresponding verbs, and when they do it is usually because they propose a simultaneous reform of the Church and the empire (as with the Reformatio Sigismundi) or because they pertain to judicial regulations (as with the 1442 ordinance addressing Vehmic courts). In short, late medieval German governmental sources speak of “reform” far less often than modern historians—an inconsistency that applies to most national historiographies of this period, as Marie Dejoux has found.³⁰ As Gabriele Annas has shown, vernacular debates about the empire were far more likely to refer to peace (Frieden) and justice (Recht, Gerechtigkeit). While commonplace across time and space in Christian Europe, this particular combination of concepts had “a highly distinct and explosive political-judicial resonance” in the late medieval empire, specifically when contemporaries alleged that peace and justice had fallen into abeyance in the German lands and needed to be restored for the sake of the common good.³¹ To these concepts, we might add “order” (Ordnung), which—as we shall see—could refer both to the social and political framework of the empire and the presence or absence of well-orderedness within it.

This semantic field did not constitute a universally agreed set of standards, but a language for articulating and contesting claims at the highest level of political activity in the empire: the interactions of the kings and emperors, prince-electors and princes, and sometimes other direct imperial members, such as the free and imperial cities. In employing a vocabulary of peace, justice, and order in this context, political actors asserted their stake and role in imperial governance. Given the diversity of the Reichsglieder, various goals and motivations could lie behind this shared normative discourse.³² We have seen that it was paired with calls to reform the Church between the 1410s and 1440s—not only in the works of anonymous radicals, but in Emperor Sigismund's own proclamations.³³ Of the most direct relevance to the period after 1453 was the increasingly prominent role of the prince-electors, and especially the three Rhenish prelates (the archbishops of Mainz, Trier, and Cologne), whose influence was instrumental during the anti-Hussite crusades of the 1420s and the response of the “German nation” to the schism between the Baslean conciliarists and Pope Eugenius IV in the 1430s–40s.³⁴ Jakob von Sierck, archbishop of Trier (r. 1439–56), was an especially prominent figure in this connection. Perhaps owing to his appointment as Frederick III's chancellor in 1441, and his exceptionally energetic activity as a zealous ecclesiastical reformer, ardent conciliarist, and shrewd administrator, Sierck became a spokesman of sorts for the Rhenish bloc of prince-electors until his death in 1456.³⁵ The close contact between the highly educated personnel of the three archbishops, and the recurrence of the same issues in their correspondence, makes it clear that Sierck's pronouncements reflected a consensus among the spiritual prince-electors about the major challenges facing the Holy Roman Empire.³⁶ In what has aptly been described as a “strategic paper” drawn up by Sierck's leading councilors in the summer of 1452,³⁷ a series of well-worn talking points about disorder and injustice came together to justify proposals for change.³⁸ Titled “The means by which the empire can be restored,” these were quite ambitious, including a supreme court explicitly compared to the parlement of Paris and a division of the empire into districts under captains.³⁹ Yet this could not be undertaken without the emperor, the ultimate fount of legitimacy in the empire, with whom the prince-electors needed to collaborate for mutual benefit: “For through us the emperor will be respected and we through the emperor. . . . [O]ur nation is the master over all other nations, as long as it is in just order and under good government.”⁴⁰

This was still a proposal in the mold of the conciliar epoch, however, for the spiritual prince-electors' councilors tied these governmental plans to a new council, per the 1417 decree Frequens, to rein in alleged papal abuses.⁴¹ What was missing was a justification for urgent change that all parties would accept as valid, and which could be used as leverage to compel the emperor and other potential opponents to co-operate. As we shall now see, sudden and widespread concern about the dangers of Ottoman invasion forced the crystallization of this discursive field into a sustained back-and-forth dialogue on “reform” in the empire—whether in the form of vague appeals to peace, justice, and order or, increasingly, concrete proposals like those of Jakob von Sierck—the better to repel the Turks in a crusade.

Fear of the Turks, Crusading Zeal, and the “Pressure of the Public”

The fall of Constantinople had a near-instantaneous impact on political discourse in the Holy Roman Empire. Once a secondary concern,⁴² the topic of the Turks now dominated letters, ordinances, and recesses at the diets and at power centers throughout the empire, accompanied by declarations about the obligation to defend Christendom against them—a situation that would persist for decades. News of Mehmed II's victory on 29 May 1453 reached Vienna within a month, Pope Nicholas V issued a crusading bull against the Turks on 30 September, and by December his legate Giovanni Castiglione had reached Frederick III to implore the emperor to spearhead the defense of Christendom. In the intervening time, sensationalist accounts of Constantinople's capture circulated throughout the German lands, in the vernacular as well as Latin.⁴³ Thus, when Frederick's summons on 11 January 1454 to the Regensburg diet made reference to “the notable and unconscionable evil of the infidel Turks,” graphically described their “many and various acts of bloodshed,” and exhorted the imperial princes and cities to plan “for praiseworthy resistance and an expedition against the enemies of Christ,” his chancery was already drawing on well-established tropes.⁴⁴

The emperor's rhetorical embrace of this role as an admonisher about the impending Turkish threat and an initiator and leader of a potential crusade is readily understandable, despite the difficulties facing him in his hereditary lands (which would, indeed, prevent him from attending the diets of Nuremberg and Frankfurt in 1454).⁴⁵ As the highest-ranking figure in Christendom, contemporaries regarded it as his duty to lead its defense, and his honor was at stake. These ideas were all on display in Castiglione's oration before Frederick on Christmas Eve in 1453, delivered during the papal legate's stay in Wiener Neustadt, the most important stop in his tour of Central Europe in late 1453 and early 1454. Castiglione's address to Frederick culminated with the exhortation: “be the wisest and most vigorous leader of this cause, who, for the sake of the defense of the Church and the faith, assumed the governorship of such a great realm that you no longer call yourself ‘king’ but by the supreme name ‘emperor.’”⁴⁶ Within the empire there was a centuries-long tradition of regarding the king or emperor of the Romans as the “advocate” or “protector of the Church(es)” (advocatus ecclesiae/ecclesiarum), a role that had recently been reinvigorated by the ecumenical councils held in the German lands.⁴⁷ These expectations help to explain the determination with which Frederick's personnel pushed a Turkish crusade—a determination that could be exploited to force negotiations over governmental reform.

Yet it is important to understand that the other political elites in the empire were also regarded (and regarded themselves) as having an obligation to contribute to the protection of Christendom. Meager though the concrete outcomes of this professed obligation may have been, it was nevertheless a normative expectation with a long history. As Heribert Müller put it, the “communis opinio” in diplomatic circles was that the task of preparing a Turkish crusade belonged first and foremost to the political community of the empire, alongside the emperor.⁴⁸ The prince-electors, in particular, had honed this sense of shared mission toward the Church and Christendom through the schisms and the Hussite crusades. In a 1424 alliance, the electors had declared their obligation to combat enemies of Christendom and pacify the empire in collaboration with the monarch and “other princes, counts, lords, knights, retainers, cities … as it rightly falls to Christian princes and the Holy Roman Empire's foremost members [‘nehsten geliedern’] to do.”⁴⁹

It is worth emphasizing how saturated with performative concern about the Turks the sources produced in elite circles during the 1450s and 1460s are. It was evidently a matter close to mind for leading princely personnel—the rising caste of university-educated councilors (gelehrte Räte) and administrators who served as diplomats and orators.⁵⁰ This does not only apply to Frederick III's personnel, like Johannes Hinderbach, bishop of Trent, who penned an obsequious oration about defending Christendom against the Turks for Pope Pius II (r. 1458–64) in April 1459.⁵¹ These themes are equally prevalent in the writings of councilors who flitted among Frederick's shifting coalitions of antagonists, and who were no friends of the papacy either—people like Gregor Heimburg, Martin Mair, and Georg von Stein, who variously served Archduke Albrecht VI of Austria, Duke Ludwig IX of Bavaria-Landshut (r. 1450–79), and George of Poděbrady, Hussite king of Bohemia (r. 1458–71), among others.⁵²

In one sense, this is hardly surprising. A constant stream of papal legates and nuncios—including Castiglione in 1454–55, Juan Carvajal in 1455–61, Bessarion in 1460–61, and Fantino della Valle in 1466—traversed the German lands in these years.⁵³ Their role was not only to drum up support and distribute indulgences for planned anti-Ottoman crusades, but also to arbitrate in the conflicts between the kings and princes of Central Europe. The popes harangued German princes from afar, too, reaching a crescendo of admonition about the planned crusade (“negocio fidei contra Turchos”) during Pius II's congress of Mantua in 1459.⁵⁴ The deployment of tropes about the Turkish threat can therefore be seen, on one level, as an organic mimicking of a Curial crusading discourse encountered frequently at diets and in writing, which could comfortably be incorporated into letters and speeches for princes who already saw defending Christendom as part of their public identities. Even opponents of specific papal and imperial initiatives still expressed vague support for the general notion of an expedition against the Turks—as Heimburg did in his orations at the Mantuan congress on behalf of Albrecht VI (on 29 October) and Sigmund of Austria-Tyrol (on 21 November), and Mair did in a speech at the court of Francesco Sforza, duke of Milan, in February 1460.⁵⁵ Alongside these diplomatic influences, genuine fear and fascination may also have played a role in some instances. Shortly after news of the fall of Constantinople reached Austria, Georg von Stein produced a Latin treatise on the Prophet Muhammad for Archduke Albrecht, drawing on traditional Islamophobic invective to portray him as an “arch-heretic” who had misled “the Saracens, Turks, and other profaners of God.”⁵⁶

In itself, the sudden rise in salience of the Turkish issue in princely circles provides an important context for the new dynamic explored in the next section. Furthemore, the sense of public expectation that shaped political actors' options in the 1450s and 1460s is even more comprehensible if we consider the much broader interest, in many social circles, in the Turks and crusading—and thereby put the fields of diplomatic history and Verfassungsgeschichte into dialogue with literary scholarship and the cultural history of identities. It is now well established that what we might consider elite conversations and discourses reached broad audiences in late medieval Europe, located within multiple overlapping public spheres.⁵⁷ It can be difficult to establish precisely who participated in these spheres, given the fragmentary nature of the evidence, but German literary scholars working with the concept of Publizistik have shown that the quantitative explosion of new texts, written and disseminated on ever-cheaper paper, strongly implies that growing and increasingly literate audiences existed for “political” writings in a variety of genres, from learned treatises to songs.⁵⁸ Particularly in German cities—the empire's main vectors of travel, commerce, and correspondence, and the sites for its political assemblies—large circles of readers and listeners engaged with a range of texts, especially those in the vernacular, and beyond the written materials that survive lay a penumbra of oral, visual, and performative communication on similar themes.⁵⁹ As Karoline Döring has shown, these were contexts ripe for disseminating news, rumors, and prophecies about the Turks in a range of media—especially as the “Turkish diets” coincided strikingly with the advent of the printing press in Mainz.⁶⁰ Its impact on discussions about the Ottomans was immediate: the oldest complete printed text to survive is the so-called Türkenkalendar, actually a poem in a mix of Rhenish dialects titled “A call to arms to Christendom against the Turks.” It consists of an opening prayer and twelve stanzas corresponding with months of the year and lunar cycles, more than half of which directly admonish the emperor and imperial princes, prelates, nobility, and cities to fight against the Ottomans.⁶¹ It can be firmly dated to late December 1454, shortly after the diet of Frankfurt at which Aeneas Silvius Piccolomini (the secretary of Frederick III and future Pius II) had given his famous oration on the same theme, Constantinopolitana clades.⁶² The Türkenkalendar's metal type was redeployed by one of Gutenberg's workshops to print Pope Callixtus III's bull Cum his superioribus (June 1456) authorizing indulgences for prayers for victory against the Turks, including—tellingly—a vernacular translation.⁶³

Already in the 1450s and 1460s, contemporaries took up the theme of the Turkish threat and the need for a military response in a multitude of literary genres, from apocalyptic prophecy to the eccentric Sultansbriefe, ostensible letters from the Ottoman sultan that could express both crusading zeal and social critique.⁶⁴ Particularly striking in this context is the work of Michel Beheim, one of the most prolific fifteenth-century German lyricists, who dedicated a large number of poems and songs to the issue of the Turks, most of which can be dated firmly to the period 1453–67.⁶⁵ Beheim participated in the Belgrade crusade of 1456, and spent these years traveling between the Upper German princely courts. His patrons included both the emperor and some of his mortal enemies, such as Count Palatine Friedrich “the Victorious.”⁶⁶ Beheim's compositions that relate to the Ottomans emphasize themes common to Turcica with particular insistence: the atrocities committed by the Turks against Christians; the blow to Christendom's prestige inflicted by the conquest of Constantinople and lands in the Balkans; the imminent danger of deeper invasions into Hungary and Germany; and the obligation incumbent on Christians, especially the neglectful German nobility, to fight back.⁶⁷ These themes influenced urban as well as courtly literature. Around 1454–56 Hans Rosenplüt of Nuremberg penned a Shrovetide play featuring Sultan Mehmed and his advisors in conversation with German knights, burghers, councilors, and messengers of the emperor and pope, presenting Turkish victories as a punishment for Christians' sins.⁶⁸ It survives in seven manuscripts, the most of any Rosenplüt play.⁶⁹ That he considered this a suitable theme for a civic performance suggests that the issue of the Turks was known and considered relevant across a wide range of social milieux soon after the fall of Constantinople.

Many more such examples could be added here,⁷⁰ but it should already be clear that the aftermath of the fall of Constantinople in the German lands stimulated a vivid and broadly based public interest in the Ottomans and the appropriate Christian response to their advance. Furthermore, the events of these years gave the texts that attest to this interest—which have mostly been analyzed by religious and literary scholars so far, and not by historians—a political valency. All this surely exerted what John Watts has called “the pressure of the public”: late medieval protagonists had to present and carry out their objectives and actions in light of “the common stock of political expectations and languages” shared among many social groups, and this now included signaling their commitment to repelling the Turks.⁷¹ In this sense, 1453 marked a new era in the empire's political discourse, as its “internal” affairs now always had to be connected to the external Turkish threat, with significant consequences for the dynamics of political interactions within it.

From Constantinople to Nuremberg: Negotiating the “Turkish Crusade” and “Imperial Reform,” 1453–67

Ever since Aeneas Silvius Piccolomini's famous bon mot about diets existing only to replicate themselves (“fecunde sunt omnes diete, quelibet in ventre alteram habet”),⁷² commentators on the mid-fifteenth-century empire have struggled to escape the conclusion that this was a period of endless futile assemblies that lacked meaningful outcomes. Only in recent decades have some historians begun to conceptualize diets as serving purposes beyond institutional change and policy decisions. The symbolic rituals accompanying diets instantiated the empire's political community and broadcast its professed values, provided a site for the hierarchies within it to be performed and re-negotiated, and created at least a fragile impression of consensus while allowing space for behind-the-scenes power struggles.⁷³ As we have seen, after the fall of Constantinople concern about the Turks and a putative crusade to defend Christendom instantly became one of the key elements of the shared political discourse to which all political actors at the imperial assemblies had to pay lip service, whatever their interpersonal rivalries and the (largely unknowable) genuineness of their commitment to the crusading cause. Consequently, proposals to restore peace, justice, and order in the empire—whatever their authors actually intended them to entail—became inextricably linked to crusading plans. More specifically, with the Turkish threat now a focal point of the empire's ostensible mission to preserve Christendom, new “reformist” initiatives could be presented as a necessary corollary or, indeed, precondition to any German-led crusade.

This logic, and the durable dynamic of back-and-forth negotiation between the emperor and princes who proposed “reformist” initiatives that it unleashed, manifested itself immediately and influentially at the “Turkish diets” of 1454–55. This is most obvious in the speech given by the councilor Johannes von Lieser in May 1454 at the diet of Regensburg, on behalf of Jakob von Sierck and the other spiritual prince-electors. The impact of the speech is attested by its wide manuscript circulation in German and Latin (the latter version being Piccolomini's paraphrase) and re-use in many later orations and treatises.⁷⁴ In the German version—an approximation, though probably not verbatim transcript, of Lieser's words⁷⁵—he fully acknowledges the threat posed by the Turks and the need for a crusade, but states: “If the unbelieving Turks are to be resisted, the prince-electors consider it necessary above all things that our most gracious lord the Roman emperor should come to suitable and customary locations and cities in the empire . . . and establish the empire and German tongue, with its courts and jurisdictions, and all its necessities, in good order.”⁷⁶ Piccolomini's account has Lieser putting this even more succinctly, in a phrase that epitomizes the rhetorical stance of would-be reformers at the heart of the new post-1453 dynamic: “it therefore seems to me that there can be no agreement to take up arms against the Turks unless we first restore the empire to its former condition.”⁷⁷

This stance prevailed among the key power brokers at the subsequent diets. At Frankfurt, a notional plan for a crusading army was made contingent on a vague two-year peace-ordinance.⁷⁸ At the follow-up discussions at Wiener Neustadt in February 1455, Jakob von Sierck personally sought to negotiate its implementation with Frederick III as a precursor to raising crusading contingents. The emperor was willing to contemplate a general peace backed by the threat of the imperial ban and excommunication, but the archbishop argued “that this would be insufficient to establish a peace in the empire, for obedience is now so reduced … that the proclamations and penalties would be entirely disdained.”⁷⁹ For Sierck and the envoys of the other prince-electors, the planned crusade could only succeed when the empire's many internal conflicts were convincingly resolved, and he had arrived with fresh proposals to that end. At their core, they involved an effective supreme court administered by the emperor with the assistance of the prince-electors, and mutual assistance among princes, lords, and cities in enforcing peace-keeping judgements, concluding that “if this takes place, and if the Holy Empire is established in good order within the German lands, we will be able to resist the Turks and other infidels mightily.”⁸⁰ However, Frederick III did not take up Sierck's ideas. He was unable to leave his hereditary lands, as the prince-electors were demanding, due to recurrent crises there. It may also be that these proposals seemed to threaten his Justinianic view of his own monarchical prerogatives. Heinrich Koller has suggested, based on Frederick's own writings, that the emperor was a jealous guardian of the juridical rights and administrative powers that he held to belong to the imperial dignity, and delegating the wholesale oversight of peace-keeping to various princes may have struck him as a step too far at this point.⁸¹ In any case, the crusade plans remained similarly theoretical, and the diet ended in mid-April amid suggestions to hold another assembly soon.⁸²

Although Frederick himself would not attend another diet in person until 1471, the new dynamic of simultaneous negotiations over the Turkish threat and internal reform proved durable. Spurred on by papal and legatine enthusiasm for a crusade, the “reformist” prince-electors could continue to claim that defending Christendom entailed urgent measures to restore peace, justice, and order. The Rhenish archbishops met in Frankfurt in February 1456 and gained the tentative approval of the other prince-electors to issue an ultimatum to Frederick. In view of the urgent need for a crusade, they demanded in the name of all the German prince-electors that the emperor appear at a planned diet in Nuremberg later that year to continue the conversations about reform.⁸³ Sierck's death in May 1456 did not prevent the prince-electors from summoning several princes and cities to the diet, some of whom duly sent envoys.⁸⁴ On 10 September, ahead of the diet and as news of Mehmed II's advance on Belgrade reached Germany,⁸⁵ they once again challenged Frederick to appear to complete the reform and crusade deliberations of Frankfurt and Wiener Neustadt:

for if you do not appear in Nuremberg at the aforenamed time, we will then nevertheless appear together with God's help in order to deliberate, to negotiate, and to reach decisions regarding everything that appertains to us as prince-electors and is necessary for the promotion of the crusade [‘kristenlichen zugs'].⁸⁶

Frederick, however, was unable to appear. His chancery sent an irate reply on 19 November, challenging the electors' right to convoke diets independently, and mounting a tellingly elaborate defense of all his work to bring a crusade against the Turks to fruition: “Now, for our part, we have expended great effort on the same matter for the consolation of the Christian faith vis-à-vis the Papal See (during the time of Pope Nicholas V and now that of our Holy Father Pope Calixtus III) and all Christian kings, you yourselves, and other princes of the Holy Empire, spiritual and temporal, for the praiseworthy promotion of the matter, at the diets held for this purpose and elsewhere.”⁸⁷

Amid this growing rancor, Count Palatine Friedrich contemplated having himself crowned king of the Romans by his allies in the electoral college.⁸⁸ A draft electoral alliance to this effect drawn up at the 1456 Nuremberg diet, though a dead letter from its inception, attests to the continuing power of the crusading project as a legitimizing discourse to enable action in the name of peace and justice. It begins by lamenting “the fall of the Christian city of Constantinople” to “the might of the Turks and enemies of our Christian faith,” emphasizing that improvement of the empire's courts and proper enforcement of the peace were necessary “so that, for the sake of resistance against the infidels and the strengthening of Christendom . . . a crusade may be deliberated about and undertaken.”⁸⁹ Count Palatine Friedrich and Dietrich Schenk von Erbach, archbishop of Mainz, were the driving forces behind both this putative alliance and yet another diet in Frankfurt in March 1457, where the talking points remained the same as positions hardened. Frederick III wrote to several imperial cities in February 1457 forbidding them from attending it, contending that the prince-electors were only convoking the diet “under the appearance of [dealing with] the Turkish matter” (“in schein der Turken sach”), and promising to send envoys of his own to discuss the best way forward for a crusade.⁹⁰ The increasingly tense exchanges between Frederick and his opponents in 1456–57 make it clear that the crusade project was now an overwhelmingly important source of legitimization for political action in the empire, and not only the emperor but also the reform-minded electors had to present their agendas as serving that project.

Although they did not lead to any official crusading expedition, to the frustration of the emperor and Curia, the discussions of the 1450s were productive in an important sense. They established the commitment to defending Christendom against the Turks as a baseline expectation in imperial politics that all sides had to claim to uphold, while clarifying some concrete initiatives that key princely factions were seeking to pursue in the name of peace, justice, and order. The growing divergences manifested in the exchanges of 1456–57 presaged the outbreak of a series of interrelated wars that consumed most of the central and southern German lands intermittently until the mid-1460s.⁹¹ Even amid these conflicts, the furious diplomatic efforts of Pius II at Mantua in 1459–60 and Cardinal Bessarion's travels and personal interventions among the German princes at diets in 1460–61 ensured that a crusade, potentially predicated on internal reform, remained a live issue.⁹² At an assembly in Vienna in September 1460, for instance, the princely envoys informed Bessarion and Frederick III that the empire urgently needed a peace-ordinance (“gemeiner Frieden”) to be promulgated before the expedition negotiated at Mantua could begin.⁹³ In 1461, Diether von Isenburg (one of the claimants to the archbishopric of Mainz), the Count Palatine, and the margrave of Brandenburg revived the dynamic of the 1450s, writing to Frederick III to request his attendance at a planned diet in Frankfurt (which never materialized) to discuss improved governance, in view of the absence of peace and justice in the empire, “which renders it ineffective at accomplishing and administering the defense of the Christian faith, and especially at offering resistance against the infidel Turks.”⁹⁴

By the mid-1460s, more than a decade had passed of Frederick III being unable or unwilling to meet the demands of some German princes for improved peace-keeping and judicial mechanisms in the empire as a precondition to a crusading expedition—one that would enhance his reputation, satisfy the Curia, and repel a power that was expanding toward Austria. In 1466, with the most disruptive internal conflagrations and rivalries largely resolved and Pope Paul II resuming demands for a Turkish crusade through another legation to Germany, conditions at last struck him as propitious to compromise on acceptable terms with the reform-minded princes and cities. The emperor signaled his openness to the issue early in that year, convoking a diet in Ulm “to make a start on the collective peace.”⁹⁵ A treaty and ordinance for banning feuds, obliging mutual assistance against peace-breakers, and streamlining the resolution of disputes was indeed drafted there and in Nördlingen by a group of south German princes and cities during the spring.⁹⁶ At another, better-attended diet in Nuremberg in November 1466, convoked so that the legate Fantino della Valle could issue another urgent call for crusading contingents from Germany, the assembled representatives refined these draft ordinances into a five-year, empire-wide peace, “so resistance can be offered all the more praiseworthily, and fully without hindrance, against the Turks.”⁹⁷ The Landfrieden treaty and ordinance included an unusual provision that flattered Frederick's own exalted sense of monarchical authority: to break the peace was to commit a “crimen laesae Majestatis,” subject to the highest notional penalties.⁹⁸

Frederick approved the peace from afar in August 1467, and his chancery's preamble speaks eloquently of the compromises that had led to this moment since the fall of Constantinople. The emperor emphasized his many efforts to promote both a crusade and imperial reform (noting his 1442 ordinance) but acknowledged that “our said reformation of peace and our faithful efforts on behalf of a crusade against the Turks have still not borne fruit as we had hoped.” Reaffirming his desire to launch a crusade in defense of Christendom and the empire, he conceded that “our and the empire's prince-electors, princes (spiritual and temporal), prelates, counts, lords, and cities have deemed and counselled … that the German nation cannot send anybody to fight the Turks unless a collective, praiseworthy peace lasting five years is ordained beforehand”—and so he was promulgating the Landfrieden.⁹⁹ The post-1453 dynamic of back-and-forth negotiation in the shadow of the Ottoman threat had culminated in a significant legislative outcome. While wars with Burgundy and Hungary would soon provide yet more impediments to a crusade, reformists had proved capable of leveraging the universally professed need for such an expedition to obtain what some factions of princes had sought since the “Turkish diets”: a framework for enforcing peace and justice as an essential precondition for any crusade preparations.

Conclusion

The peace-ordinance of 1467, though largely ineffective in the short term, was not the only outcome of the new political dynamic identified in this article. It would serve as a template for many subsequent iterations, as institutional changes gathered momentum at imperial diets in the decades around 1500.¹⁰⁰ The fall of Constantinople can therefore be considered one of the catalyzing factors for the institutional “reforms” that are often regarded as the turning point between the medieval and early modern history of the Holy Roman Empire, suggesting that “imperial reform” or Moraw's “organized consolidation” (gestaltete Verdichtung) ought to be defined more broadly to include significant developments earlier in the fifteenth century. The sudden increase in the salience of the Turkish threat and the sense of crusading mission in the empire created a new political dynamic at the diets. This mission provided a focal point for discussions at these assemblies, which quickly crystallized into a particular negotiatory format: against the background of a range of voices drawing on the potent reservoir of discourses about peace, justice, and order in the empire, a cadre of princely councilors articulated concrete “reformist” proposals, and was able to force these onto the agenda as the counteroffer for commitments to contribute to a planned Turkish crusade. Whatever their personal motives and inclinations, all parties had little choice but to present themselves as caring deeply about crusading projects, given the widespread concern about the Turks in German-speaking public spheres, ensuring that advocates of peace-keeping and judicial initiatives had plenty of opportunities to present their proposals to influential political actors.

Neither crusading rhetoric nor “reformist” discourses were new in the mid-fifteenth-century Holy Roman Empire. Even the notion that internal peace was a precondition for successful crusading had a long heritage.¹⁰¹ However, in the febrile atmosphere that followed the fall of Constantinople, the semantic field of “imperial reform” and plans for the defense of the empire and Christendom became publicly and durably fused in a new way, setting up a long-term dynamic whose logic would not only endure in connection with anti-Ottoman expeditions, but would also be extended to negotiations over military aid against French, Hungarian, and Italian antagonists. That the “reforms” or “consolidation” of Maximilian's reign were long-term outcomes of a dynamic predicated on the threat posed by a religious “Other” to Christendom highlights the continuing relevance of universal, pan-Christian frames of reference alongside emerging articulations of national solidarity and political pluralism, and echoes recent scholarly findings about the significance of religious and ethnocultural logics in shaping late medieval European identities.¹⁰²