Career
Casselman joined the Canadian Forces in 1916. He served in the Canadian Expeditionary Force and then the Wiltshire Regiment until 1919. Casselman served a long career as an Edmonton municipal politician, he served as a Public School Trustee from 1928 to 1937.
In 1937 he resigned his Trustee seat and ran for Alderman winning a seat.
He held his Aldermanic post until he resigned in 1940 to run for the Canadian House of Commons. Casselman ran in the 1940 Canadian federal election in the Edmonton East as a candidate for the Liberal Party of Canada.
Casselman died a year into his 1st term in office on March 20, 1941, at age 55.