The British rejoicings upon the occupation of their snug winter-quarters in New York were suddenly interrupted, early on the morning of September 21st, by the breaking out of flames from a low groggery near Whitehall Slip, which, for want of proper fire apparatus to check them, spread rapidly over one fourth of the city, consuming five hundred buildings, including the Lutheran and Trinity churches. Whether this was the work of incendiaries is not positively known. Congress and the city's inhabitants had strenuously opposed such an act, though it was strongly recommended as a military necessity by Washington and by others of high rank and position. While Howe "continued at gaze" awaiting coming events, Washington continued to strengthen his position on Harlem Heights, and established alarm posts on the east side of Harlem River as far as Throg's Neck on the Sound, to insure surveillance of the whole field of operations. The Harlem lines being too strong for a front attack, Howe, after leaving a sufficient force under Lord Percy to watch them and guard the city, embarked, October 12th, his main army on ninety flatboats, to execute by his favorite manœuvre the turning of these obstacles and of Washington's left flank. His object was to cut off Washington's retreat and shut him up on Manhattan Island, the only exit from which was by Kingsbridge. Adverse winds so delayed the British general that he only passed Hell Gate on the afternoon of the 14th, and the fleet did not reach Throg's Neck till nightfall. Here Howe had previously landed his advance-guard, but Washington had anticipated him by occupying, on the 12th, the passes leading to the mainland. The enemy's design being now fully developed, it was decided in a council of war, held in the American camp on the 16th, to leave Harlem Heights, no longer tenable, and to evacuate the whole of Manhattan Island except Fort Washington, which General Greene deemed impregnable and of great value for future operations. Accordingly, the American army formed a series of intrenched camps on the hills skirting the right bank of the swollen Bronx, and extending thirteen miles, from Fordham Heights to White Plains, and protected from the enemy by the river in front. After waiting five days for supplies, Howe, on the 18th, left Throg's Neck, debarked again on Pell's Point, and on the march northward encountered Glover's brigade well posted behind stone fences. After a hot skirmish Glover slowly fell back, while the enemy advanced to the heights of New Rochelle. Here the British encamped till the 22d, when they were joined by the second division of Hessians under General Knyphausen. This delay gave Washington ample time to strengthen himself at White Plains, where he held a strong and important strategic position commanding the roads leading up the Hudson and to New England.