The formation of the Canadian Corps as an mainly Canadian composed military unit was not the result of planning or political rational, but the natural progression of the building up of Canadian formations in Europe. The first Canadian Division had been sent to England in 1914, trained on the Salisbury Plain and then crossed over to France to engage in the fighting. The second Canadian Division was formed and by September 1915 had crossed over to France to join in the fighting.
On the previous April 1st, Colonel Carson had written a letter to Sam Hughes the Canadian Minister of Militia which suggested that the 2nd Canadian Division should be assigned to Corps command with the 1st Canadian Division and thus form a wholly Canadian Corp. Up until this point the largest military unit in the British military that would usually be considered as undividable was the Division so that as Corps and Armies were formed, broken up and reformed on a continuous basis it was with these Divisions as the building blocks. Hughes followed this suggestion up when he suggested to the British General HQ through his military liaison officer, Lieutenant Colonel J.J. Carrick that it was "the earnest desire of all of Canada" that a Canadian Corp be formed and maintained as a Canadian force which would eventually be increased to 3 Divisions.
The communication was presented to Sir John French who commanded British troops on the Western Front and he immediately dispatched Carrick to London to suggest the formation of the Corp to Lord Kitchener, the commander in chief of the British and Empire forces, with a strong recommendation that the suggestion be accepted. Australian and New Zealand forces had already combined into a similar force with positive results. Kitchener considered a commander for the Corp and viewed General Alderson who had the confidence of the Canadian troops and officers, as capable of command the Corps. French concluded with "I think vest return we can make for splendid service rendered by Canadian Division is to meet their wishes."
Kitchener concurred with all of these suggestions and June 15th the British Secretary of State for the Colonies communicate to the Canadian Governor General that the Army Council believed that it would be advantageous for the two Canadian Divisions to be joined together into a permanent Canadian Corp as soon as the 2nd Division took the field. The idea caught on n Canada and almost immediate organizational arrangements were begun to provide the Corps infrastructure support for the formation. Sam Hughes and Prime Minister Robert Borden were both in England during that summer and the realization of military and political benefits of a Canadian Corp were immediate and hence their support for the initiative was strong.
On September 3, 1915 the Corp HQ was established by General Alderson with his successor as 1st Division Commander be assigned to Major General Arthur Currie who would become the most distinguished Canadian Commander of the First World War. This also meant that the Canadian Corp would be in a position to fight large scales battles on their own an hence generate and enhance a proud feeling of Canadian nationalism which was to reach it's apogee at the Battle of Vimy Ridge.