sentences:  In 1938 he joined Canada's Department of External Affairs, but was recruited for the Prime Minister's Office in 1940 to be a speechwriter and protocol expert.Gibson accompanied Mackenzie King on several diplomatic missions — including his two wartime strategy sessions with the U.S. and British governments in Quebec City — and in 1945 he was part of the Canadian delegation to the first United Nations conference in San Francisco.Gibson left the federal government in 1947 for a teaching position at Carleton College (later Carleton University) in Ottawa.