September 1777: The Battle of Brandywine, a major engagement in the American Revolutionary War, takes place. The British army under General William Howe defeats the Continental Army under General George Washington, and the Patriots retreat to Valley Forge.
December 19, 1777: The Continental Army arrives at Valley Forge, a small village located about 20 miles northwest of Philadelphia.
January 1778: The harsh winter begins, and the soldiers are ill-equipped to handle the cold and snowy conditions. Many suffer from exposure and disease, and supplies are scarce.
February 1778: Friedrich Wilhelm von Steuben, a German-born officer, arrives at Valley Forge and begins to train the soldiers in discipline and military tactics.
May 1778: The French formally enter the war on the side of the Patriots, providing troops, supplies, and naval support.
June 1778: The Patriots launch a successful surprise attack on the British forces at the Battle of Monmouth, but the British retain control of Philadelphia.
July 1778: The Patriots successfully defend against a British attack at the Battle of Barren Hill.
December 1778: The Patriots abandon Valley Forge, as the British army is occupied with actions in the southern colonies.
October 1781: The British army under Lord Cornwallis surrenders at the Battle of Yorktown, effectively ending the war in the Patriots' favor.
September 3, 1783: The Treaty of Paris is signed, officially recognizing the independence of the United States from Great Britain.