Because of these minor successes, Magaw became overconfident; he boasted of being able to hold the fort through a siege to the end of December. On November 2, Magaw's adjutant, William Demont, deserted and supplied British command with detailed plans of the fortifications. Percy sent the information on to Howe, who had defeated Washington a few days earlier at the Battle of White Plains. During the weeks between Washington's northward retreat and the British assault on the fort, reinforcements continued to trickle in to the fort, increasing the size of the garrison to nearly 3,000 men.