Pattison enlisted at Calgary, Alberta on 6 March, 1916. On 10 April 1917 at the Battle of Vimy Ridge when the advance of Canadian troops was held up by an enemy machine-gun which was inflicting severe casualties, Private Pattison, with utter disregard of his own safety, sprang forward and jumping from shell-hole to shell-hole, reached cover within thirty yards of the enemy gun. From this point, in the face of heavy fire he hurled bombs killing and wounding some of the crew, and then rushed forward overcoming and bayoneting the surviving five gunners.
His initiative and valour undoubtedly saved the situation.
He was killed in action at Lens, France, on 3 June 1917. He is buried at Louisiana Chaudière Military Cemetery, France located 7 miles north of Arras (plot IV, row C, grave 14).
A mountain in the Victoria Cross Ranges in Jasper National Park, Alberta is named in his honour.