This point having been ascertained, General Howe, on the 12th, leaving Percy in command before Harlem Heights, moved the greater part of his army nine miles up the East river to Throg's Neck, a peninsula in the Sound, separated from the mainland by a narrow creek and a marsh that was overflowed at high tide. By landing here suddenly, Howe hoped to get in Washington's rear and cut him off from his base of supply in Connecticut. But Washington had foreseen the move and forestalled it. When Howe arrived at Throg's Neck, he found the bridge over the creek destroyed, and the main shore occupied by a force which it would be dangerous to try to dislodge by wading across the marsh. While Howe was thus detained six days on the peninsula Washington moved his base to White Plains, and concentrated his whole army at that point, abandoning everything on Manhattan Island except Fort Washington. Sullivan, Stirling, and Morgan who had just been exchanged, now rejoined the army, and Lee also arrived from South Carolina. [Sidenote: Baffled at White Plains, Howe tries a new plan] By this movement to White Plains, Washington had foiled Howe's attempt to get in his rear, and the British general decided to try the effect of an attack in front. On the 28th of October he succeeded in storming an outpost at Chatterton Hill, losing 229 lives, while the Americans lost 140. But this affair, which is sometimes known as the battle of White Plains, seems to have discouraged Howe. Before renewing the attack he waited three days, thinking perhaps of Bunker Hill; and on the last night of October, Washington fell back upon North Castle, where he took a position so strong that it was useless to think of assailing him. Howe then changed his plans entirely, and moved down the east bank of the Hudson to Dobb's Ferry, whence he could either attack Fort Washington or cross into New Jersey and advance upon Philadelphia, the "rebel capital." The purpose of this change was to entice Washington from his unassailable position. [Sidenote: Washington's orders in view of the emergency]