In September 1944, Simonds temporarily took charge of the First Canadian Army from Lieutenant-General Harry Crerar, who was recovering from a bout of dysentery, and led the liberation of the mouth of the Scheldt River. "By most accounts, Simonds’ assumption of command reinvigorated the army HQ; where Crerar managed, Simonds commanded." When Crerar resumed command with the First Army, Simonds resumed his command of II Canadian Corps for the liberation of North-Western Europe.