The Mackenzie–Papineau Battalion or Mac-Paps were a battalion of Canadians who fought as part of the XV International Brigade on the Republican side in the Spanish Civil War in the late 1930s. Except for France, no other country had a greater proportion of its population volunteer in Spain as did Canada. The XV International Brigade, made up also of volunteer battalions from the United States and Britain, was involved in the Battle of Jarama, in which nine Canadians are known to have been killed.