Ethan Allen and the Green Mountain Boys captured Fort Ticonderoga in May 1775, and also participated in the invasion later that year of the Province of Quebec. In the latter effort, Allen was captured following a poorly-organized attempt to capture Montreal in September 1775. Allen was held as a prisoner of war by the British until May 1778, when he was exchanged for a British officer. During much of the time, he lived in New York City on parole and was, by his own account, approached in late 1776 by a British officer with an offer to join the British side.