Why did Washington try to defend New York in 1776?

The British troops were under siege. They defended the Patriots and suffering very high casualties. Washington ordered Troops to take command of the New York defense.

When the American Revolutionary War broke out in April 1775, British troops were under siege in Boston. They defeated Patriot forces in the Battle of Bunker Hill, suffering very high casualties ... In January 1776, Washington ordered Charles Lee to raise troops and take command of New York's defenses.