James Monroe was involved in many of the American Revolution's major events before leaving the military in 1780. He joined the army as a lieutenant in 1776 and over time rose to the rank of lieutenant colonel. Further, he earned the respect of his fellow soldiers, especially George Washington who called him “brave, active, and sensible.”
Crossing the Delaware and More
James Monroe crossed the Delaware with George Washington to fight at the Battle of Trenton where he was wounded and received a commendation for his bravery. He was aide-de-camp to Lord Stirling during the winter at Valley Forge. He fought at Brandywine, Germantown, and Monmouth, including serving as a scout for Washington during the latter battle.
Restless Under Lord Stirling
In 1778, James Monroe decided to leave Lord Stirling's service to try and create his own command out of volunteers from Virginia.
Lord Stirling was actually a man named William Alexander who had claimed the title of his ancestors in Scotland though his claim was never fully accepted by the British government. He was extremely heroic and well respected by Washington. In fact, he was given command of the Northern armies in 1781. He died before the end of the war.
On this front he was not successful. In 1780, Governor Thomas Jefferson made him military commissioner of Virginia. He would never again enter active duty, instead devoting his life to public service.