However, the 1st Canadian Infantry Division took part in the Italian Campaign, participating in the Moro River Campaign and the Battle of Ortona in December 1943 as part of British V Corps and it was not until the fourth Battle of Monte Cassino (Operation Diadem) in May 1944 that I Canadian Corps fought its first battle as a corps. The Eighth Army held the corps in reserve until after the Gustav defences in the Liri valley had been broken and then brought it forward to assault successfully the next defensive line, the Hitler Line, shortly before the Allied capture of Rome in early June. Having taken part in the Allies' northward advance to Florence, the corps then took part in Operation Olive, the assault on the Gothic Line, in September 1944 before being transported during January–February 1945 in Operation Goldflake to rejoin the rest of the First Canadian Army in Belgium and the Netherlands. There the corps participated in the campaign to complete the liberation of the Netherlands. On May 6, 1945, at Wageningen, Lieutenant-General Foulkes received the final surrender by Colonel GeneralJohannes Blaskowitz of all remaining German forces still active in the Netherlands. The corps was deactivated on July 17, 1945, as part of general demobilization.
Although nominally a Canadian formation, I Canadian Corps contained significant elements at different times from other Allied countries. For example, in Italy, during the assault on the Gothic Line in the fall of 1944, the corps included the British 4th Infantry Division, the 2nd New Zealand Division and the 3rd Greek Mountain Brigade. During the final campaign to liberate the Netherlands, the corps included for a time the British 49th Infantry Division.
^Col. C. P. Stacey, Official History of the Canadian Army in the Second World War: The Canadian Army 1939-1945: An Official Historical Summary, Department of National Defence, Ottawa, Canada, 1948.