While current law, ("e.g.", United States Code Title 10 (relating to service members in the U.S. Navy and Marine Corps), beginning in 1918, explicitly states that recipients must be serving in the U.S. Armed Forces at the time of performing a valorous act that warrants the award, exceptions have been made. Apart from these rare exceptions, Medals of Honor can only be awarded to members of the U.S. Armed Forces, although being a U.S. citizen is not a prerequisite. Sixty-one Canadians who were serving in the United States Armed Forces have been awarded the Medal of Honor, with a majority awarded for actions in the American Civil War. Since 1900, only four have been awarded to Canadians. In the Vietnam War, Peter C. Lemon was the only Canadian recipient of the Medal of Honor.