Canadian training for D-Day had begun as early as July 1943, when Lieutenant-General Andrew McNaughton of the First Canadian Army informed Harry Crerar, commander of II Canadian Corps, that the 3rd Canadian Infantry Division might play a role in the invasion of France. Initial training was demanding, and complicated by the lack of any landing craft to practice with, either LCAs or LCTs. Field exercises in Scotland commenced in August and September 1943, and succeeded in establishing unique techniques and equipment for use by armoured and artillery regiments in storming the beach; the most significant were the amphibious "Duplex Drive" tanks (DD tanks). Mechanisms were also developed to allow artillery to bombard the beach while still aboard their landing craft. Through the winter of 1943, units jointly developed more advanced assault tactics among the Juno regiments.