In colonial times, the island was used mainly for farming. During the American Revolution, the British forces under Captain James Wallace raided Prudence Island for livestock and engaged in a skirmish with American forces, losing approximately a dozen soldiers. In the 20th century, farming began to decline and the island began to attract summer residents. In World War II, the Navy established an ammunition depot on the southernmost of the island. In 1972, the Navy turned the base over to the State of Rhode Island, leaving bunkers, roads, and a large deep-water pier.