John Riley (soldier)

John O'Riley
Born	8 February 1817 Clifden, Ireland
Died	10 October 1850(1850-10-10) (aged 33) Veracruz, Mexico
Allegiance	United Kingdom  United States Mexico
Service/branch	British Army  United States Army  Mexican Army
Years of service	1835–1840 (UK) 1845–1846 (US) 1846–1850 (Mexico)
Rank	Sergeant (UK) Private (US) Brevet Major (Mexico)
Commands	Batallón de San Patricio
Battles/wars	Mexican–American War Siege of Fort Texas Battle of Monterrey Battle of Buena Vista Battle of Cerro Gordo Battle of Churubusco

John Patrick Riley (also known as John Patrick O'Riley) (Irish: Seán Pádraig Ó Raghallaigh) (8 February 1817 – 10 October 1850) was an Irish soldier in the British Army who emigrated to the United States and subsequently enlisted in the United States Army. During the Mexican–American War of 1846–1848, Riley led several other Defectors in the ranks who defected to Mexico, where they formed the Saint Patrick's Battalion in the Mexican Army.