OTTAWA – A roofing salesman who studies Canada’s military past in his spare time has prompted the country’s professional historians to rethink one of the great controversies of the First World War: the success – or not – of the conscription policy that created a deep national divide along French-English lines.

Michel Gravel, a history buff from Cornwall, Ont., has unearthed what appears to be a significant error in the traditional calculation of how many conscripted soldiers were sent into battle before the end of the war.

And the find has been hailed as “a great service to scholars” by none other than Jack Granatstein, the dean of Canadian historians.

Generations of war chroniclers – most notably Granatstein himself, author of a book on the subject, as well as the conscription entry in the Canadian Encyclopedia – have accepted the figure of 24,132 compulsory recruits who reached the front lines in Europe.

Gravel probed the conscription question while researching his recently published biography of Ottawa native Sgt. Hillie Foley, a long-overlooked hero from the First World War.

The part-time researcher discovered evidence that as many as half of the supposed Canadian conscripts were actually Britishborn Americans who volunteered for overseas duty through a U.S.-based recruitment drive orchestrated by British patriots in North America.

The British-American recruits were sent north to enlist in Canada until mid-1918, when the U.S. military announced its own draft.

“The error came about because both volunteers obtained by the recruiting missions in the U.S.A. and conscripts raised in Canada were assigned regimental numbers from the same block (3,000,000 to 4,000,000),” Gravel writes in an appendix to his book about Foley.

“This made it impossible to tell the American volunteers apart from the Canadian conscripts. … The contribution to the great Canadian victories of 1918 by these late-war volunteers from the U.S.A. has never been examined.”

Gravel’s conclusions about the conscription numbers have impressed Granatstein.

“Gravel launches a full frontal assault on the standard and accepted numbers of conscripts who went overseas in 1918. I’m one of the people he attacks, and I’m afraid I must agree that he is likely right,” Granatstein writes in Legion magazine.

“By studying regimental numbers, by examining the late war volunteers for the Canadian Expeditionary Force recruited in the U.S., Gravel has forced me to reassess matters. The Military Service Act of 1917 clearly worked less well than the politicians – and the historians – believed.”

The act was passed in August 1917 by the wartime Conservative government of Robert Borden. Opposition to the plan in French Canada was intense and nearly universal, prompting realignments in Parliament and riots in Quebec in response to a measure that forced thousands of young men to fight in what some Canadians viewed as an essentially “foreign” war.

The much lower number suggested by Gravel’s research could erase any doubts about whether conscription was worth the trouble it caused for Canada.