The initial fort was an earthen fortification constructed by Taylor's troops and called "Fort Texas." When Taylor marched a large portion of his troops to Point Isabel (now Port Isabel), he left a garrison, under the command of Maj. Jacob Brown, to guard the fort. Taking advantage of the situation, the Mexican Army attacked the fort, sending part of their force to engage the main portion of Taylor's force as it returned from Point Isabel . Taylor defeated the Mexicans at the Battle of Palo Alto (May 8) and at Resaca de la Palma (May 9). These engagements were the first battles of the Mexican War, and the most important battles of the war fought on U.S. soil. Following these defeats, the Mexican Army fled back across the Rio Grande. The fort was renamed Fort Brown in honor of Major Brown, who was killed in its defense. Fort Brown remained active from the Civil War through the early 20th century and was abandoned as an army post in 1944. The buildings that remain date from the post-Civil War era. A small portion of the earthwork fort remains as well.