He joined the
British Expeditionary Force (BEF) in
France in 1939 and 1940, commanding a
machine gun company of the 2nd Battalion, Cheshire Regiment, which was attached to
Major-General Harold Alexander's
1st Infantry Division. During the retreat from the
River Dyle in the face of the German
blitzkrieg in May 1940, his company formed part of the division's rearguard, supporting the
13th/18th Royal Hussars and 21st Anti-Tank Regiment of the
Royal Artillery. He was awarded the
Military Cross (MC) for his actions, and was
evacuated from Dunkirk. He spent most of the war on a variety of staff appointments, and married Victoire Marion Williams-Freeman in 1942. Promoted to lieutenant-colonel, he was appointed as
Commanding Officer (CO) of the 1st Battalion,
Manchester Regiment, in March 1944. The battalion (formerly the 6th Battalion, a
Territorial Army before being redesignated as 1st Battalion in May 1942), serving as the machine gun battalion of the
53rd (Welsh) Infantry Division, a first-line TA formation commanded by Major-General
Robert Ross, was poorly trained and virtually unfit for duty, but Harington quickly brought it to full combat readiness. The battalion, along with its parent division, landed in
Normandy, France, in late June, three weeks after the
Normandy landings, and was engaged in severe fighting throughout the
Battle of Normandy, and most of the subsequent
fighting in Western Europe, until Harington relinquished command in mid-September 1944, when he became a
General Staff Officer Grade 1 (GSO1) with the 53rd Division HQ. He retained this post until May 1945. For his services as CO of the 1st Manchesters, Harington was awarded the
Distinguished Service Order DSO in early 1945. ==Post-war service==