The naval Battle of La Rochelle of 1419 took place between a Castilian and an allied Flemish-Hanseatic fleet. The Castilian victory resulted in their naval supremacy in the Bay of Biscay. but it also led to a protracted conflict with Flanders and the Hanseatic League, which ended in 1443 with further commercial concessions to Castile. The battle was notable for the use of guns by the Castilian fleet.