Located on the southwest edge of town, Fort Clark was occupied by Texas troops after secession and the surrender of U.S. posts to provide protection against Indians. The troops seized the four 24 pounders and two 8-inch howitzers there and sent the cannon for use in defense of the Texas coast. The fort also stood on the supply line for the Arizona and New Mexico campaign to make the South an ocean to ocean nation. Although the frontier defense line was pulled east more than 50 miles in 1862 and posts were set a day's horseback ride apart from the Red River to the Rio Grande, Fort Clark remained occupied by Confederate and State troops to keep Indian uprisings in check, protect against bandits from Mexico, and constantly watch for U.S. invasion along the Rio Grande.