American Revolution/American Retreat through New York and New Jersey
In October, General Howe moved to encircle the American Army stationed on northern Manhattan. In response, Washington had the Army retreat off the island, into the Bronx. Howe continued to give chase to the American Army, but Washington responded by halting his army and chose a position near White Plains that he fortified.
Battle of White Plains 
Although the British outnumbered the Americans, Howe did not think it was wise to launch an attack on the main American position until they had taken Chatterton Hill, a strategic hill in the area of White Plains Howe decided to send Alexander Leslie and his brigade, along with 3 regiments of Hessians to take the hill. In total, the force numbered about 4,000 men. The British forded the Bronx, and were fired upon by American guns on the other side of the river.
The first attempt to take the American positions failed, as they offered stiff resistance. Another attempt was made to take hill, with a Hessian regiment going around the back of the hill to attack the American Flank. As the main assault began to push the Americans back, the Hessian Regiment came in from behind and the Americans retreated, taking their cannon with them.
While the battle was a victory for the British, Howe refused to interfere with the American withdrawal, letting slip yet another opportunity to capture Washington and much of the Continental army and in the process suffering heavier casualties than the Americans.
Fort Washington 
Instead of continuing to follow Washington north, How turned his army south and decided to launch an attack on the key American Fort, Fort Washington. It was the last American stronghold on the island of Manhattan.
On the morning of November 16, 1776, around 8,000 British and German troops, under the command of Howe, attacked Fort Washington. Although the American garrison put up a fierce struggle, they were forced to surrender when the British and Hessian forces managed to breach their walls with cannon fire. The fall of Fort Washington was a great loss of men and supplies for the American forces. The garrison lost around 53 men killed in action, 96 more wounded, and the rest (totaling 2,818 men) became prisoners of war. Knyphausen reported his casualties at 78 dead and 374 wounded during the storming of the fort.
Four days later, the isolated Fort Lee(located across the river from Fort Washington) was evacuated, leaving behind most of the fort's women, gunpowder and other arms to fall into British hands. With the collapse of both forts, the Hudson River was open from then on to British shipping, leaving the merchant ships and warships to move freely without serious harassment from the Americans.
Retreat Across New Jersey 
Washington's Command in Jeopardy 
Washington had split his army, and turned his Army south and retreated hoping to make a stand in front on Philadelphia. General Charles Lee was in charge of the other group.
Toward the end of 1776, Lee's animosity for Washington began to show. During the retreat from Forts Washington and Lee, he dawdled with his army, and intensified a letter campaign to convince various Congress members that he should replace Washington as Commander-in-Chief. Around this time, Washington was accidentally given and opened a letter from Lee to a Colonel Reed, in which Lee condemned Washington's leadership and abilities, and blamed Washington entirely for the dire straits of the Army. Though he was the victim of the letter, Washington wasn't angry. He was suspicious and disappointed at both Lee and himself, for he (Washington) was a man that took too much responsibility and not enough credit for himself. He sent the letters to Reed and wrote an accompanying letter apologizing for the mistake. Although his army was supposed to join that of Washington's in Pennsylvania, Lee set a very slow pace. On the night of December 12, Lee and a dozen of his guard inexplicably stopped for the night at White's Tavern in Basking Ridge, New Jersey, some three miles from his main army. The next morning, a British patrol of two dozen mounted soldiers found Lee writing letters in his dressing gown, and they captured him. Among the members of the British patrol was Banastre Tarleton. Lee's Army then turned south to regroup with Washington. Lee was eventually recouped by the colonial forces in an exchange for General Richard Prescott.
Howe sent General Lord Cornwallis to chase Washington's army through New Jersey. Cornwallis continued to chase the Americans until they withdrew across the Delaware River into Pennsylvania in early December. With the campaign at an apparent conclusion for the season, the British entered winter quarters. Although Howe had missed several opportunities to crush the diminishing rebel army, he had killed or captured over 5,000 Americans. He controlled much of New York and New Jersey and was in a good position to resume operations in the spring, with the rebel capital of Philadelphia in striking distance.