Joseph M. Chadwick, military and topographical engineer and acting adjutant general under Fannin at Goliad, was born in Exeter, New Hampshire, in April 1812, the son of Peter Chadwick. He was admitted to the United States Military Academy at West Point on July 1, 1829, but resigned on April 30, 1831. He lived for several years in Illinois before his arrival about December 25, 1835, at Velasco, Texas, where he was appointed sergeant major of William Ward's Georgia Battalion. The unit sailed to Copano and arrived at Refugio in January 1836, but fell back to Goliad, where it became part of James Walker Fannin, Jr.'s provisional regiment. Although he was defeated by Dr. Warren J. Mitchell in the election for regimental major by an 81–73 vote, Chadwick was appointed acting adjutant general when Fannin reorganized his staff about the middle of February 1836. As a military and topographical engineer Chadwick mapped Fort Defiance (La Bahía) for his commander, and with John Sowers Brooks supervised the fortification of the Goliad presidio. Lewis M. H. Washington, who also served on Fannin's staff, described Chadwick as having "a native suavity of temper and urbanity of manner, which at once made him the Pride of the battalion."
Chadwick was sent to ensure Ward's prompt return from his mission to relieve Amon B. King at Refugio but got lost and returned to Goliad. With Fannin and Benjamin C. Wallace, he signed the articles of surrender to Gen. José de Urrea following the battle of Coleto and returned to Goliad a prisoner. On March 24 Chadwick and two or three others accompanied Fannin under Mexican escort commanded by Lt. Col. Juan Holzinger on a trip to Copano to determine the availability of a ship to transport prisoners to New Orleans. The records do not reveal the result, but the party returned to Goliad on March 26. Chadwick was murdered with the rest of Fannin's command in the Goliad Massacre by order of Antonio López de Santa Anna on March 27, 1836. For his service and sacrifice in the Texas cause, Chadwick's heirs received five land grants totaling 3,820 acres by 1846.