This paper will demonstrate that I British Corps’ operations were critical to the opening of the port of Antwerp. By examining the impact that I British Corps had on the operational and strategic levels of command within Twenty-First Army Group, it challenges the narrative that their operations were supporting in nature. Anchoring the centre of a three corps operation designed to open the port of Antwerp, clear the Scheldt Estuary, and push German forces out of southern Holland, I British Corps faced the bulk of Fifteenth Army and was decisive in undermining its strategic concept of operations. In fact, I British Corps’ actions ensured the operational success of 2nd Canadian Division and the strategic success of First Canadian Army and Twenty-First Army Group.