Louis St. Laurent succeeded King as Liberal leader and Prime Minister on November 15, 1948. In the 1949 and 1953 federal elections, St. Laurent led the Liberal Party to two large majority governments. As Prime Minister he oversaw the joining of Newfoundland in Confederation as Canada's tenth province, he established equalization payments to the provinces, and continued with social reform with improvements in pensions and health insurance. In 1956, Canada played an important role in resolving the Suez Crisis, and contributed to the United Nations force in the Korean War. Canada enjoyed economic prosperity during St. Laurent's premiership and wartime debts were paid off. The Pipeline Debate proved the Liberal Party's undoing. Their attempt to pass legislation to build a natural gas pipeline from Alberta to central Canada was met with fierce disagreement in the House of Commons. In 1957, John Diefenbaker's Progressive Conservatives won a minority government and St. Laurent resigned as Prime Minister and Liberal leader.