Fort Lancaster is a former United States Army installation located near Sheffield, Texas. The fort was established in 1855 on the San Antonio–El Paso Road to protect migrants moving toward California through Texas. The US Army occupied Fort Lancaster until Texas seceded from the United States in March 1861 and were replaced at the fort by forces loyal to the Confederate States of America. The Confederate Army held the fort from November 1861 until April 1862, when it was again abandoned and then burned.