In 1847, he enlisted in Bell's cavalry detachment, of Hay's Regiment of Texas Mounted Volunteers, that served along the Rio Grande frontier in the Mexican–American War.
[3][4] In 1854 he, and his two brothers Benjamin and David and their wives, left Texas moving to El Monte in California, where he was admitted to the bar, practicing in Los Angeles.
[8] Hanks had previously purchased a one-third interest in the grant, with Amasa Lyman and Charles C. Rich leaders of the Mormon colonists of San Bernardino from the original grantee José del Carmen Lugo.
After many of the El Monte Boys were persuaded to return to their homes, Bethel sheltered Ainsworth at his adobe house with the aid of some friends and relatives, including his brother David.
[12][13]: 1, col.2 [14]: 95–96 [15]: 95–96 [16] : 419–420 [17] In the bitterly contested campaign of 1860, Charles W. Piercy was nominated for member of the 1st District of the California General Assembly by one party, and W. A. Conn the incumbent, by the other.
The accusation was that polls at Temescal, maintained by a resident named James Greenwade, kept open shop for three weeks and that whenever candidate Piercy was in need of more votes, they were furnished from this precinct.
After the Battle of Peralta he and his Spy Company were responsible for saving the remnants of Sibley's army, 1800 men, from Union pursuit by finding water and a path for them through the rugged mountains west of the Rio Grande to the Mesilla Valley.
There he was nearly killed and his brother, David, drowned after being shot by troops of Juan Cortina while traveling on the steamboat Bell on the Rio Grande.
He contributed articles to and wrote book reviews for early issues of the Texas State Historical Association Quarterly, in which he published "Notes on the History of La Bahía del Espíritu Santo" in 1898–99 and "The Route of Cabeza de Vaca" in 1899–1900.