That election brought the federal Progressive Conservative Party of Canada to power under John Diefenbaker.

During World War II, he served with the Royal Canadian Air Force as a navigator and flight lieutenant.

After the war, he ran three times unsuccessfully as the Progressive Conservative candidate for the Canadian House of Commons in the 1945, 1949, and 1953 elections.

He ran in the riding of Regina East in the 1968 federal election, and lost by 192 votes to the New Democrat candidate.

From 1960 to the 1963 election, when the Diefenbaker government was defeated, Hamilton served as Minister of Agriculture, pioneering wheat sales to the People's Republic of China.