Simpson began serving with the Canadian Expeditionary Force in March 1918. He was a member of the first group of official war artists sent to record Canada's participation in the conflict by Lord Beaverbrook, joined by Frederick Varley, J.W. Beatty, and Maurice Cullen. This painting likely depicts the moment before a battle in the series of attacks known as Canada's Hundred Days which began with the Battle of Amiens, 8-12 August 1918.

During this period, the Canadians gained a reputation as a formidable force as they repeatedly spearheaded offensives. The British Prime Minister David Lloyd George wrote, 'The Canadians played a part of such distinction that thenceforward they were marked out as shock troops; for the remainder of the war they were brought along to head the assault in one great battle after another. Whenever the Germans found the Canadian Corps coming into the line they prepared for the worst'.