Richard Lee Clark papers concerning the Civil War

Fort Welles was originally a Confederate fort called Fort Walker on Hilton Head Island in South Carolina. After the Battle of Port Royal Sound in November of 1861, the Union Army occupied the fort and changed its name to Fort Welles in honor of Gideon Welles, the U.S. Secretary of the Navy. The Union Army established a base next to the fort that eventually housed 40,000 troops. One of the main reasons the Union Army wanted to capture the fort was to provide a logistics base to support the blockade of other Southern ports. To aid in this effort, the Army built a long pier adjacent to the fort and installed a rail system to offload supplies from cargo ships coming in from the North and then load blockading vessels with those supplies. The fort remained in Union hands for the duration of the war and was changed to the Post of Hilton Head in April 1866 to cover all of the remaining military facilities on the island. In January of 1868, the Post was abandoned and the military left the island for good.

Source: http://www.fortwiki.com/Fort_Welles