John Twohig, San Antonio merchant and banker, was born in Cork County, Ireland, in April 1806. After serving as an apprentice on a British merchant vessel and engaging in coastwise trade between New Orleans and Boston, he established a mercantile business in San Antonio, Texas, in 1830 and took part in the siege of Bexar in 1835. At the time of the Adrián Woll invasion of San Antonio in September 1842, Twohig blew up his store to keep ammunition from the enemy. Captured and taken to Mexico, he and fourteen other San Antonians held in Perote Prison cut a tunnel and effected their escape on July 2, 1843; Twohig was one of nine not recaptured. He returned to San Antonio, became a banker, and was widely known for his breadline for the unfortunate. This breadline, which he financed personally, was continued by his sister for several years after his death. In April 1853 Twohig married Bettie Calvert of Seguin. In the years prior to the Civil War he amassed a large personal fortune. His banking business declined because of the effects of the war, but soon recovered. In 1870 Twohig was among the 100 wealthiest men in Texas, with real property estimated at $90,000 and personal property worth an additional $50,000. He died at his home in San Antonio in October 1891.