Final answer:
Honoré Mercier called for the Interprovincial Conference to address issues such as conscription during WWI, which was especially controversial in Quebec, as well as other national issues like health and minority rights.
Step-by-step explanation:
Honoré Mercier likely called for the Interprovincial Conference to address significant national issues affecting the provinces, including the controversy over conscription during World War I, particularly as it related to Quebec's contribution to the war effort. During World War I, the Canadian government under Prime Minister Sir Robert Borden faced the challenge of needing more soldiers due to heavy casualties in battles such as Vimy Ridge. The issue of conscription was contentious, particularly in Quebec where there was significant opposition. The Union government, which was a coalition of Conservatives and pro-conscription Liberals, had to govern through a period of deep division within the country, marked by bitter election and conscription riots. Mercier may have seen the Interprovincial Conference as a way to bring provinces together to discuss their concerns and find solutions to maintain unity and address pressing national problems, such as military recruitment, national health, and protection of minority rights like those of French Canadians and the Métis.