Truce of Adrianople

Through this treaty, Ferdinand I of Austria and Charles V recognized total Ottoman control of Hungary,[1] and even agreed to pay to the Ottomans a yearly tribute of 30,000 gold florins for their Habsburg possessions in northern and western Hungary as a buffer for Vienna.

When Louis II of Hungary fell at Mohacs fighting the Turks in 1526, his crown was thrown to the Habsburgs.

The agreement bought the Catholic Habsburgs peace on their eastern frontier so they could answer the German Protestant Princes in the west, which coalesced to the Thirty Years War, 1618-1648.

The truce was the result of a triangular affair with John Sigismund Zápolya, Voivode of Transylvania.

It wasn't until the truce expired in 1551 that Ferdinand I asserted as legitimate his claim to all of Hungary.