Immediately after his arrival in Texas he joined the resistance movement against Mexico. He participated in the battle of Gonzales on October 2, 1835. Shortly afterward he assisted his uncle, Bailey Hardeman, and others in bringing a cannon from Dimmitt's Landing to San Antonio for use against Mexican forces under Gen. Martín Perfecto de Cos. Hardeman and his brother Thomas Monroe Hardeman accompanied a small relief column to the Alamo, but the garrison had fallen to Mexican forces shortly before their arrival. The Hardemans abandoned their exhausted horses and after a narrow escape on foot suffered severe hunger. Gotch was then sent by his uncle Bailey on an errand to summon militia. An illness resulting from exposure on this assignment probably kept him from action in the decisive battle of San Jacinto. He subsequently served for a number of years in the Texas Rangers. He accompanied Erastus (Deaf) Smith for four months of ranger duty on the frontier in 1837 and fought in Col. John Henry Moore's ranger force against the Comanches at Wallace's Creek on February 22, 1839. Three months later he participated in the Córdova campaign in East Texas, an aftermath of the Córdova Rebellion.
Hardeman fought the Comanches in the battle of Plum Creek on August 11, 1840. In February 1842 he engaged in harassment of invading Mexican forces led by Gen. Rafael Vásquez. Nine months later he joined the Somervell expedition against Mexico. After the annexation of Texas by the United States, Hardeman served as a member of Benjamin McCulloch's Guadalupe valley rangers in Gen. Zachary Taylor's army. He engaged in the exploration of the Linares, China, and Cerralvo-San Juan River routes to the Mexican stronghold of Monterrey and scouted ahead of Taylor's main invading force. Hardeman's last Mexican War engagements were in the scouting expedition to Encarnación and the ensuing battle of Buena Vista. Subsequently he went to his Guadalupe County plantation, where he farmed with as many as thirty-one slaves.
Fifteen years later he returned to military life. After voting for secession in 1861 as a member of the Secession Convention, he raised a force from Guadalupe and Caldwell counties, forming the 800-man Company A of Col. Spruce M. Baird's Fourth Texas Cavalry Regiment, part of Henry H. Sibley's New Mexico Brigade. He fought and was twice wounded at Valverde, where he participated in the successful charge against Alexander McRae's battery of artillery (the Valverde Battery), after which he was promoted to regimental major. In April 1862 Hardeman commanded the successful defense of the Confederate supply depot at Albuquerque against Col. Edward R. S. Canby's much larger force and was credited with saving the artillery. After the defeat of Sibley's column, Hardeman was reassigned to the Gulf theater of war. He participated in Gen. Richard Taylor's Red River campaign, which turned back the numerically superior army of Union general Nathaniel P. Banks, and eventually rose to the command of the Fourth Texas Cavalry. After successful campaigns at Yellow Bayou and Franklin, Hardeman was promoted to brigadier general.
After the surrender of Gen. Robert E. Lee at Appomattox, Hardeman, like his cousin Peter Hardeman and thousands of other Confederates, became an exile. He joined a company of fifteen high-ranking officers, eluded Gen. Philip H. Sheridan, and escaped to Mexico. There he served briefly as a battalion commander in Maximilian's army and became a settlement agent for a Confederate colony near Guadalajara. In 1866 he returned to Texas, where he served as inspector of railroads, superintendent of public buildings and grounds, and superintendent of the Texas Confederate Home in Austin. He also helped avert bloodshed in the Coke-Davis controversy of 1873-74 and was one of the founders of the Agricultural and Mechanical College of Texas (now Texas A&M University). Hardeman was twice married, first to his uncle Bailey's widow Rebecca, and after her death to Sarah Hamilton. He had two children by the first marriage and five by the second. He died of Bright's disease on April 8, 1898, and was buried at the State Cemetery in Austin.
30° 15.917, -097° 43.631
Texas State Cemetery