Clinton, along with Major Generals William Howe and John Burgoyne, was sent with reinforcements to strengthen the position of General Thomas Gage in Boston. They arrived on 25 May, having learned en route that the American War of Independence had broken out, and that Boston was under siege.

Clinton replaced General Howe as Commander-in-Chief of North America. Looking to capitalize on some of the success the British experienced the previous year, particularly at Savannah, Georgia, Clinton turned his attention to the Southern Colonies. In 1780, Clinton initiated a siege of Charleston, South Carolina and eventually forced the surrender of the city. This marked a major British victory and sparked a campaign to secure South Carolina.

Despite Cornwallis’s prominent role in the loss and surrender, Clinton, as Commander-in-Chief, was blamed for the loss of the American colonies. After the Revolution, he published a narrative account of the war in an attempt to clear his name. By 1793, Clinton became a full general and received an assignment as Governor of Gibraltar. He died before he could assume the post.