Summer Time was first introduced during the First World War. However, most countries discontinued the practice after the war. It was then restarted in various countries during the Second World War and its immediate aftermath. Again it was widely cancelled by the 1950s, but reintroduced in isolated cases until the late 1960s, when the energy crisis of the late 1960s and early 1970s began to prompt policymakers to reintroduce Summer Time across the continent. It has remained in place in most European countries since then.