The regiment was primarily responsible for defending the coast of the United States against enemy attacks, and it served in this role until the end of the war.

In 1941, the regiment was stationed at Fort Mills in the Philippines, where it played a critical role in the defense of the islands against the Japanese during World War II.

During the Japanese invasion of the Philippines in December 1941, the 51st Coast Artillery Regiment provided crucial support to the defenders of the islands.

In April 1942, after months of fierce fighting, the 51st Coast Artillery Regiment and the other defenders of Bataan were forced to surrender to the Japanese.

After the Armistice the regiment turned in its heavy equipment and was moved back to the United States, where it was rearmed with 24 8-inch howitzers.

A Gold color metal and enamel device 1+1⁄4 inches (3.2 cm) in height overall consisting of a shield blazoned: Gules on a bend Or a caterpillar passant Vert.