Final answer:
Robert Borden introduced conscription because voluntary enlistment was not sufficient to meet military demands, especially with the high casualties and lower recruitment levels in Quebec. The need for more troops in Europe and reduced enthusiasm for voluntary service contributed to the decision.
Step-by-step explanation:
Robert Borden decided to introduce conscription in June 1917 primarily due to a lack of volunteer recruits. The severe casualties suffered at battles like Vimy Ridge, and the insufficient number of volunteers, especially from Quebec, made it clear that voluntary enlistment would not meet the military demands. Quebec was contributing fewer volunteers partly because its majority were farmers needed at home for the war effort, and French Canadians felt disconnected from the English Canadians' patriotic fervor for Britain's war. Moreover, across Canada, the early war enthusiasm had waned, and some resisted enlistment due to pacifist beliefs or skepticism about the war's worth. Borden's forcing of conscription was also influenced by military officials who urged the need for more troops in Europe, leading him to introduce the Military Service Act.