The most significant battle of the Revolutionary War in terms of combatants was the Battle of Brooklyn, also known as the Battle of Long Island. It took place on August 27, 1776, marking the first significant engagement after the Second Continental Congress unanimously adopted the Declaration of Independence on July 4, 1776.
The battle involved over 40,000 troops, including a fleet of over 400 Royal Navy ships, warships, and 32,000 British troops under the command of Admiral Richard Howe. Unlike the earlier success against the British at the Siege of Boston, General George Washington's Continental Army faced a challenging situation in Brooklyn. British forces cornered Continental troops in Brooklyn Heights, forcing the Continental Army to shrewdly evacuate 9,000 soldiers during the dark of night to Manhattan using flat-bottomed ferry boats across the East River.
Although avoiding being captured, this allowed Britain to secure control of New York City's ports until the end of the Revolutionary War. Even today, five Army National Guard units and one Regular Army Field Artillery Battalion trace their origins to the American units that fought in this battle.