Thomas Washington Cox, Baptist preacher and soldier, was born in Alabama in 1815 and immigrated to Texas in 1838 or 1839. In 1840 he was living in Fayette County, where he owned 300 acres of land, a gold pocketwatch, and one metal clock. He soon organized and was elected pastor of churches at La Grange, Travis, and Independence and was named the first moderator of the Baptist Union Association in the state. As moderator, he called for the first convention of Texas Baptists in June 1840. He became a follower of the teachings of Alexander Campbell, however, and, according to nineteenth century Baptist historian John B. Link, "serious reports of bad conduct followed him from Alabama." In 1841, therefore, after confrontations with Z. N. Morrell, he was excluded from the church in La Grange and retained the pulpit of the other two only by narrow margins. "He afterwards became more interested in horse-racing and gambling than in preaching," wrote Link.
Cox was elected justice of the peace for Fayette County on January 20, 1842, but soon thereafter was elected second lieutenant in Capt. William M. Eastland's Company B of Brig. Gen. Alexander Somervell's Army of the South West. Cox participated in the Somervell and Mier expeditions, was captured at the battle of Mier, and took part in the escape attempt led by Ewen Cameron at Salado on February 11, 1843. He was one of only four of Cameron's men to make his way back to Texas, the others being recaptured and subjected to decimation by firing squad after the notorious Black Bean Episode.
On September 16, 1849, the anniversary of the release of the Mier prisoners, Cox introduced a motion to a meeting at La Grange to form a monument committee to raise funds for a memorial to the dead of the Mier expedition and the Dawson Massacre. He also proposed that the remains of Nicholas M. Dawson's and William S. Fishers's men be reinterred on Monument Hill (see MONUMENT HILL-KREISCHE BREWERY STATE HISTORICAL PARK). He was the only Mier man named to the Texas Monument Committee. On September 16, 1850, Cox, called "a man of great eloquence," met with the Mier and Dawson survivors at a reunion at Monument Hill and delivered the main address of the observation.
When Robert S. Neighbors returned from his reconnaissance into what is now New Mexico in 1850 and reported that area's intention of setting up an independent territorial government, the citizens of Fayette County appointed Cox to a committee to report on the "insurrectionary movements in the county of Santa Fe." Cox's committee considered New Mexico's actions "an outrage upon the State of Texas" and resolved to call upon the government of the United States to maintain Texas sovereignty there. Failing assistance from the national government, however, the members of the committee proposed to equip a "military force to put down the insurrection" and threatened secession from the Union if the state's boundaries of December 19, 1836, giving Texas all of New Mexico east of the Rio Grande, were not respected. Cox died in Bastrop County on February 6, 1852, of what the Austin Texas State Gazette called "congestion of the brain."