For 1537 important combined operations had been agreed upon between France and the Ottoman Empire as part of the Franco-Ottoman alliance, in which the Ottomans would attack southern Italy and Naples under Barbarossa, and Francis I would attack northern Italy with 50,000 men. Suleiman led an army of 300,000 from Constantinople to Albania, with the objective of transporting them to Italy with the fleet. The Ottoman fleet gathered in Avlona with 100 galleys, accompanied by the French ambassador Jean de La Forêt. They landed in Castro, Apulia by the end of July 1537, and departed two weeks later with many prisoners. Barbarossa had laid waste to the region around Otranto, carrying about 10,000 people into slavery. Francis however failed to meet his commitment, and instead attacked the Netherlan