As a private in the 41st, Byfield saw heavy action during the Anglo-American War of 1812. In the conflict's western theatre, he served at the Siege of Detroit and the Battle of Frenchtown, where he was wounded in the shoulder, as well as at the Siege of Fort Meigs and the Battle of Fort Stephenson. Byfield narrowly escaped capture after British defeat at the Battle of the Thames and later rejoined elements of his regiment in the Niagara Peninsula. Byfield participated in the Capture of Fort Niagara and the Battle of Lundy's Lane, but his left arm was shattered by a musket ball at the Battle of Conjocta Creek, an unsuccessful British raid on 3 August 1814 preceding the Siege of Fort Erie. Byfield's forearm was subsequently amputated and he was invalided back to England, where he was awarded a pension from the Royal Hospital Chelsea in 1815.