Harrison started his training in Regina in the summer of 1942. He arrived in England in July 1943, and completed more training. In March 1944, he was posted to 431 (Iroquois) Squadron.

One training trip was a bombing run over the marshalling yards in Amiens, France, with Harrison up front to observe the approach and landing. On return, a 500lb bomb was jarred loose on landing and exploded underneath the aircraft on the runway. Harrison was one of the crew that was blown from the aircraft, receiving a flash burn to the left forearm. The injury deteriorated and Harrison was transferred to QVH, where 58 patches of skin were grafted to his arm by Dr. Tilley.

He returned to active duty after treatment, surviving a bail out over the Lake District. On his last trip, on 30 November 1944, one of his engines was shot out over Duisburg in the Ruhr. Harrison managed to complete his bombing run and return to base, but his landing gear would not go down. He was directed to a nearby crash airfield at Carnaby, Yorkshire, where, on final approach, his other engine cut out. His landing gear snapped when they made contact with the ground, and the aircraft came to a halt, safely with no casualties.

SSQ - Station Sick Quarters