Canadian-born men, followed by those born in the British Isles, made up the bulk of the 620,000 men who enlisted in the Canadian Expeditionary Force (CEF) during the First World War. Many Americans, perhaps 20,000 to 30,000 or more, enlisted in Canada or were recruited in the USA. Men holding Russian passports became the next most numerous group in the CEF, as recent immigrants from the vast Russian Empire joined up. How many of these were ethnic Ukrainians, born in Ukrainian regions of the Tsarist Empire? And how many ethnic Ukrainians born in the Austro-Hungarian Empire, even though it was one of the enemy Central Powers, were allowed into the Canadian army?1
"For King, not Tsar: Identifying Ukrainians in the Canadian Expeditionary Force, 1914–1918,"
Canadian Military History:
3, Article 3.
Available at: http://scholars.wlu.ca/cmh/vol17/iss3/3