There were between 30,000 to 50,000 Canadians that served with Union forces in the American Civil War, about 10,000 fought with the Confederacy and four were Generals in the Union army. John McNeil was born in Halifax, Nova Scotia and was an insurance company president in St Louis prior to the war and served out of Missouri. John Franklin Farnsworth was born in Compton City, Quebec and was an elected U.S. Representove to Illinois prior to the war and served out of Illinois. Jacob Cox was born in Montreal, Quebec and was a college professor turned lawyer prior to the war in Ohio where he served. Martin Thomas McMahon was born in LaPrairie, Quebec and was a lawyer in California prior to the war but served most of his time in the Army of the Potomac starting as an aide to General George McClellan and eventually rising to General himself.
American Civil War page