From Wikipedia: The Military Voters Act was introduced in August 1917 and gave the vote to all Canadian soldiers regardless of their period of residence in the country. A military voter would cast his ballot, not for a specific candidate, which was standard procedure for general elections, but for the current government or the opposition. If the constituency in which the voter had lived at the time of enlistment was specified, it was there that the ballot would be counted. Without a specific constituency, the vote would be assigned to a riding by the governing party. With this ability of assigning votes, the governing party was able to use the vote in a constituency that was beneficial to their party.