This chapter examines the wars that broke out in the Netherlands, at least partly because of reformation, during the final third of the sixteenth century. Militant Reformed Protestantism established itself in the Low Countries, especially in the western provinces, by the early 1560s. In 1566, the “wonderyear,” political and religious protest erupted into the open, as nobles protested Habsburg religious policy and Reformed militants sacked churches in an iconoclastic fury. This in turn caused Philip II to install a military regime, led by the Duke of Alba, in order to suppress rebellion and heresy. In 1572 the rebels won territory in the north, and by 1580 gained control of the northwestern half of the region, where Reformed militants instituted a revolutionary reformation to root out Catholicism. Sectarianism in turn caused a breakdown of the rebel alliance, and by the mid-1580s the Habsburg had successfully retaken most of Flanders and Brabant. By 1590 a military stalemate had bifurcated the Netherlands, with the rebels in control of the seven northern provinces and the Habsburgs in control of the ten southern provinces. Each region would follow its own religious trajectory.

Chapter 5 investigates the League of Landsberg’s failed attempt to admit new Protestant and Catholic territories in the early 1570s, including the Low Countries. The League’s proposed expansion presented an opportunity to create a lasting peace in the Empire by forging new ties among competing territories. At multiple points, however, both Catholics and Protestants rejected this possibility, as neither party wished to cede primary authority in the alliance. Even as the League continued to resolve neighborly disputes, support for its exercise of shared sovereignty eroded. Related processes operated in the Low Countries during the 1570s, where civil war spawned competing alliances: the Union of Arras and the Union of Utrecht. Including members that supported a variety of religious policies, the Union of Utrecht tried to solve the problem of religious diversity by devolving authority over religion to provincial governments. Such a solution meant that much of the United Provinces’ subsequent political development depended on how different provincial authorities interpreted the meaning of the Union’s treaty of alliance. This dynamic remained at the heart of the Dutch Republic and its exercise of shared sovereignty throughout the late sixteenth and seventeenth centuries.