Dearborn prepared plans for simultaneous assaults on Montreal, Kingston, Fort Niagara, and Amherstburg, but the execution was imperfect. A half-hearted advance into Lower Canada in November 1812 simply collapsed after a very minor engagement at the Battle of Lacolle Mills. Some scholars believe that Dearborn also did not move quickly enough to provide sufficient troops to defend Detroit. Hull, without firing a shot, surrendered the city to British General Isaac Brock. Hull was court-martialed and sentenced to death, but the sentence was commuted. Dearborn headed the court martial.