Wilsey served in the Second World War, as Commanding Officer (CO) of the 9th Battalion, Worcestershire Regiment in Northern Ireland and Southeast England from January−October 1943. The battalion formed part of the 182nd Brigade of the 61st Division and, although initially selected to take part in the Allied invasion of Normandy, it fid not materialise. He then served as CO of the 7th Battalion, Duke of Wellington's Regiment, which formed part of the 147th Brigade of the 49th (West Riding) Infantry Division. He led the battalion during the Allied invasion of Normandy in June 1944 and throughout the Battle of Normandy, and through most of the Northwest Europe Campaign until, in early January 1945, Wilsey was promoted to command the 158th Brigade, part of the 53rd (Welsh) Infantry Division, which he commanded for rest of the campaign in North West Europe until Victory in Europe Day in May 1945.