On 1 September 1916, Clarke's battalion was charged with capturing a 50-yard-long salient between the Canadian position at Mouquet Farm and Courcelette to the north.

Clarke, an acting corporal at the time, was assigned to take a section to clear the enemy on the left flank to allow his company sergeant to build a fortified dugout that would secure the Canadian position once the salient was overrun.

When his section reached the trench, it was so heavily defended that they had to battle their way through with hand grenades, bayonets and their rifles as clubs.

"[1]The account in The London Gazette differed from the experiences related by Leo Clarke to his brother Charles (Charlie) while recuperating shortly after the events of 9 September 1916.

As an acting corporal, Clarke was not permitted to have, wear, or use a side-arm, however he had won a Colt Model 1905 Marine Corps and two extra magazines from a group of U.S. soldiers in a card game.

According to his brother Charles, the actions of the day (and the shooting one by one of the soldiers with the side-arm) troubled Leo deeply that The London Gazette account wasn't challenged, but contributed to Clarke's lack of enthusiasm for the honour.

[2] On 11 October 1916, Sergeant Clarke's battalion was ordered forward to secure the newly captured Regina Trench which was under heavy enemy artillery fire.

He is buried in Plot II, Row C, Grave 3A, in Etretat Churchyard,[3] 16 miles north of Le Havre, France.

According to a contemporary newspaper article, shortly before his death he wrote to his parents, stating: "I don't care so much for the Victoria Cross as getting home for a couple of months."

For the first time, the Governor General of Canada, the Duke of Devonshire, travelled to make a personal presentation of the award at a ceremony attended by about 30,000 people.

In 1925, Pine Street in West End, Winnipeg, was renamed Valour Road in honour of Clarke and fellow Victoria Cross winners Frederick William Hall and Robert Shankland, all of whom lived on the 700 block.