 After many delays, the expedition began to move up the San Juan River on March 17, 1780.On April 9, Nelson—in the first hand-to-hand combat of his career—led an assault which captured a Spanish battery on the island of Bartola on the San Juan River.The siege of Fort San Juan, located five miles (8 km) upstream and manned with about 150 armed defenders and 86 others, began on April 13.