The costly wars against Venice and the devastating impact of the Black Death greatly reduced the Genoese navy's strength. The rise of larger nation states also sapped the ability of the relatively small city-state to compete militarily. Genoa (with French support) launched a crusade against Tunisia in 1390, with the intent to protect Genoese trade colonies from Muslim pirates. During the war the Genoese navy provided ships while French knights laid siege to the fortress of Mahdi. The war was a success for the Christian forces, but also resulted in the French gaining political influence in Genoa, which was pressured to declare itself a French fiefdom in 1396. The Genoese navy was brought under French control, and on 7 October 1403 was decisively defeated by Venice at the Battle of Modon after the Genoese fleet raided Venetian trade colonies. The Republic gained independence from France in 1409, but the prestige of the military had been severely damaged and the city remained a coveted political conquest for both France and Aragon. In 1435 a Genoese fleet was dispatched at the request of Milan to the town of Gaeta, which was besieged by Aragon. At the time, the Duke of Milan and the King of Aragon were fighting as to who would control the Kingdom of Sicily. The Genoese fleet arrived at Gaeta and defeated the numerically superior Aragonese fleet at the Battle of Ponza. The Aragonese flagship was forced to surrender and King Alfonso V of Aragon was captured. Despite this setback, Aragon prevailed in the conflict and Sicily came under Aragonese control, making passage through the Strait of Messina difficult and further disrupting Genoese naval activities.