[4] He grew up alongside cousin, General Edward Pakenham[3] from Castlepollard, County Westmeath, who died in the Battle of New Orleans.
[4] Fagan went to Copano, Texas, to scout the area for water, building materials, and an appropriate farmstead location prior to bringing his family.
He found a suitable location on the south bank of the San Antonio River in what is now Refugio County, then retrieved his family.
[3] The Fagans were among the earliest settlers of Power and Hewetson's Colony,[6] which was established with the purpose of settling the sparsely populated Mexican frontier with Irish Catholics.
de la Garza provided some animals to Fagan to help him get started[7] and informed him of a wrecked Spanish barkentine 20 miles away with good lumber for building a house.
[4] Fagan built the first mill in the area and provided flour, corn meal, and masa for the local ranches.
[3][8] On August 4, 1834, five years after establishing his homestead, Fagan received his land grant of 9,538 acres, part of the Power and Hewetson Colony.
[5] The Fagans lived peacefully alongside their native and Mexican neighbors until the Texas Revolution brought an influx of newcomers, including some undesirable individuals, to the region.
Like James Power, Fagan strongly opposed Antonio López de Santa Anna's efforts to centralize the Mexican government and deny Texas the right to self-governance.
[1][4] Fagan sent his wife and children to Louisiana and volunteered as quartermaster with Philip Dimmitt's company in the Texian Army, fighting with distinction[9] throughout the war.
Fagan served in Dimmitt's company from October 9, 1835, to January 20, 1836, as well as under Ira Westover and Hugh Frazer in different periods.
[1] Shortly after leaving, he ran into a hundred rancheros and Karankawa led by de la Garza and was forced to surrender.
[1] Santa Anna ordered the execution of all rebels, but de la Garza intervened and released the Mexican colonists and Fagan.
[1] Fannin was ordered to retreat by Sam Houston from Presidio La Bahía at Goliad, but delayed this action.
[1] Knowing Santa Anna's orders to Urrea to execute all prisoners, de la Garza developed a plan to help him escape.
[7] de la Garza had his men slaughter a cow and give a side of beef to Fagan to carry for them.
[6][9] Fagan, Thomas O'Connor, de la Garza, and others formed a local militia called Power and Cameron's Spy Company from 1836 to 1838.
After this, they organized in a local San Antonio River militia under John J. Tumlinson and fought in many raids and expeditions with Mexican bandits and Comanches.
[4][6] In 1838, a large contingent of Native Americans from Mexico invaded the San Antonio River bottom, killing several settlers.
[6] On September 1, 1841, Refugio was raided by a group of Mexicans led by a man named Ortegon seeking revenge.
A posse was formed with Fagan, sons John and William (born 1828), O'Connor, de la Garza, and others.