Peter Gallagher, stonemason, merchant, explorer, and land developer, was born in Westmeath County, Ireland, in 1812. In 1829 he immigrated to New Orleans, where he learned the trade of stonemason. He settled in San Antonio, Texas, in 1837 and practiced his trade there until 1841, when he joined the Texan Santa Fe expedition. His diary gives a day-by-day account of the expedition, as well as information concerning the capture and imprisonment of the Texans. After being released from prison on June 13, 1842, Gallagher returned to Texas and joined the Texas Rangers under John Coffee (Jack) Hays. From 1846 to 1850 he was engaged in the mercantile business in San Antonio. In 1850 he returned to Ireland, where he married Eliza Conran. Back in Texas, he invested in real estate and had a business in Mexico. He was chief justice (county judge) of Bexar County from 1861 to 1864. After another trip to Europe he began the development of land in the Fort Stockton area and was instrumental in the organization of Pecos County in 1877. Gallagher died in Bexar County on October 30, 1878.