In 1540 Hungary became a Turkish province and in 1543 Barbarossa bombarded Nice. Suleyman siezed the citadel of Estergon and in 1544 a new campaign was waged against Persia. Shah Tahmasb did not dare to face Suleyman and a great many castles were taken. Following an inconclusive action in 1552 Shah Tahmasb offered to make peace and, as part of the Treaty, Azerbijan, Eastern Anatolia and Iraq were added to the Empire of the Ottomans.
In 1566, while engaged in besieging the Castle of Sigetwar, Suleyman the Magnificent died. The castle fell shortly after his death and the throne was assumed by his son, Selim.
The mid-16th century also saw the triumph of the devsirme over the Turkish nobility, which lost almost all its power and position in the capital and returned to its old centres of power in southeastern Europe and Anatolia. In consequence, many of the timars formerly assigned to the notables to support the spahi cavalry were seized by the devsirme and transformed into great estates--becoming, for all practical purposes, private property--thus depriving the state of their services as well as the revenue they could have produced if they had been transformed into tax farms. While the spahis did not entirely disappear as a military force, the Janissaries and the associated artillery corps became the most important segments of the Ottoman army