The Ottoman conquest of Szigetvar and Gyula (1566) exposed the weakness of the Habsburg monarchy. Unable to mount a military response, Maximilian II depended on his diplomats to ward off the imposition of a conqueror's peace along the Hungarian border. But an official register, the Book of Halil Beg, put forward the sultan's claims to a wide swath of towns and villages, including many still held by Habsburg loyalists. Moreover, the Ottomans said, His Majesty had best accept a settlement on these terms; victorious Turkish captains wanted more and were restrained only by Selim II's orders. This essay describes the efforts of Maximilian's ambassadors to forestall additional losses in peacetime. After years of tough negotiation, they managed to obtain minor revision of the relevant treaty text. Although the Book of Halil Beg would indeed be the basis for any border settlement, as the Porte insisted, the Ottomans acknowledged that Vienna disputed certain of its provisions. This mere protest may have been enough to assure loyalist magnates in Hungary that the dynasty had not abandoned them, or their hereditary lands. Hence the paradox of Habsburg-Ottoman diplomacy. The 1576 treaty of peace, formally ending hostilities, was at the same time a charter for Kleinkrieg.