By the 16th century, the Ottomans had become a serious threat to the European powers, with Ottoman ships sweeping away Venetian possessions in the Aegean and Ionian seas and Ottoman-supported Barbary pirates seizing Spanish possessions in the Maghreb. The Protestant Reformation, the French–Habsburg rivalry and the numerous civil conflicts of the Holy Roman Empire distracted the Christians from their conflict with the Ottomans. Meanwhile, the Ottomans had to contend with the Persian Safavid Empire and to a lesser extent the Mamluk Sultanate, which was defeated and fully incorporated into the empire.