Howe remained at Scarsdale until the morning of October 28, when his forces marched toward White Plains, with British troops on the right under General Henry Clinton, and primarily Hessian troops on the left under General von Heister. While Washington was inspecting the terrain to determine where it was best to station his troops, messengers alerted him that the British were advancing. Returning to his headquarters, he ordered the 2nd Connecticut Regiment under Joseph Spencer out to slow the British advance, and sent Haslet and the 1st Delaware Regiment, along with Alexander McDougall's brigade (Rudolphus Ritzema's 3rd New York Regiment, Charles Webb's 19th Continental Regiment, William Smallwood's 1st Maryland Regiment, and the 1st New York Regiment and 2nd New York Regiments) to reinforce Chatterton Hill.
Spencer's force crossed the Bronx River, set up behind a stone wall, and exchanged fire with the Hessians led by Colonel Johann Rall that were at the head of the British left column. Eventually forced to retreat when Clinton's column threatened their flank, these companies retreated across the Bronx River, while fire from the troops on Chatterton Hill covered their move. Rall's troops attempted to gain the hill, but were repelled by fire from Haslet's troops and the militia, and retreated to a nearby hilltop on the same side of the river. This concerted defense brought the entire British Army, which was maneuvering as if to attack the entire American line, to a stop.
While Howe and his command conferred, the Hessian artillery on the left opened fire on the hilltop position, where they succeeded in driving the militia into a panicked retreat. The arrival of McDougall and his brigade helped to rally them, and a defensive line was established, with the militia on the right and the Continentals arrayed along the top of the hill. Howe finally issued orders, and while most of his army waited, a detachment of British and Hessian troops was sent to take the hill. The British attack was organized with Hessian regiments leading the assault. Rall was to charge the American right, while a Hessian battalion under Colonel Carl von Donop (consisting of the Linsing, Mingerode, Lengereck, and Kochler grenadiers, and Donop's own chasseur regiment) was to attack the center. A British column under General Alexander Leslie (consisting of the 5th, 28th, 35th, and 49th Foot) was to attack the right. Donop's force either had difficulty crossing the river, or was reluctant to do so, and elements of the British force were the first to cross the river. Rall's charge scattered the militia on the American right, leaving the flank of the Maryland and New York regiments exposed as they poured musket fire onto the British attackers, which temporarily halted the British advance. The exposure of their flank caused them to begin a fighting retreat, which progressively forced the remainder of the American line, which had engaged with the other segments of the British force, to give way and retreat. Haslet's Delaware regiment, which anchored the American left, provided covering fire while the remaining troops retreated to the north, and were the last to leave the hill. The fighting was intense, and both sides suffered significant casualties before the Continentals made a disciplined retreat....
John Fortescue... 267 British and Hessians killed, wounded or missing at White Plains. Henry Dawson, on the other hand, gives Howe's loss as 47 killed, 182 wounded and 4 missing. The American loss is uncertain. Theodore Savas and J. David Dameron give a range of 150-500 killed, wounded and captured. Samuel Roads numbers the casualties of 47 killed and 70 wounded. Henry Dawson estimates 50 killed, 150 wounded and 17 missing for McDougall's and Spencer's commands but has no information on the losses in Haslet's regiment.
The two generals remained where they were for two days, while Howe reinforced the position on Chatterton Hill, and Washington organized his army for retreat into the hills. With the arrival of additional Hessian and Waldeck troops under Lord Percy on October 30, Howe planned to act against the Americans the following day. However, a heavy rain fell the whole next day, and when Howe was finally prepared to act, he awoke to find that Washington had again eluded his grasp. Washington withdrew his army into the hills to the north on the night of October 31, establishing a camp near North Castle. Howe chose not to follow, instead attempting without success to draw Washington out. On November 5, he turned his army south to finish evicting Continental Army troops from Manhattan, a task he accomplished with the November 16 Battle of Fort Washington."