[2] During this time he served under Lieutenant-Colonel Sam Steele, and earned the Queen's South Africa Medal with four clasps.

[3] Stewart received his commission, completing his studies at the Royal Military College of Canada in February 1908 to form the 25th Artillery Battery.

[3] On the outbreak of the First World War, Stewart was asked to command the 20th Artillery Battery from Lethbridge, and was promoted to lieutenant colonel before going overseas on 9 August 1915.

The Lethbridge City electoral district was dissolved prior to the 1921 Alberta general election, which saw Stewart defeat his Labour opponent John Marsh by 978 votes.

[9] Stewart contested the 1925 Canadian federal election in the Lethbridge riding, representing the Conservative Party of Canada.

Stewart was unable to hold his seat in the 1935 election, being defeated by federal Social Credit candidate John Horne Blackmore by a wide margin of over 3,600 votes.