For most of the War, Prévost's strategy was defensive and cautious. Learning in August 1812 that the British government had repealed some of the Orders in Council (1807) which the United States regarded as a cause of war, he negotiated an armistice with commanding General Henry Dearborn, but President James Madison soon repudiated Dearborn's agreement and the war resumed. During the early months of 1813, Prévost twice visited Upper Canada where the military and civil situation was unsatisfactory after the Governor and Commander there (Major General Isaac Brock) had been killed in action. As a result, he was present in Kingston in May, and took personal charge of an attack on the main American naval base on Lake Ontario. A victory here could have been decisive but the expedition was hastily mounted and at the Battle of Sackett's Harbor both Prévost and the naval commander, Commodore James Lucas Yeo, attacked hesitantly. After meeting stiff resistance, they withdrew.