Who became Senior Officer of the U.S. Army after George Washington resigned in 1783?

General George Washington resigned as Commander-in-Chief of the Continental Army on December 23, 1783 and the post was renamed to "Senior Officer of the U.S. Army". Major General Henry Knox assumed the post following Washington's resignation. He would serve as Senior Officer until June 1784.

Henry Knox, a Boston bookseller, volunteered his services during the Siege of Boston and Bunker Hill, in directing artillery and siege fortifications. General Washington was impressed with his work during those battles and with the help of John Adams, was commissioned Colonel of the army's artillery regiment. Later, promoted to Brigadier General and named "Chief of Artillery", he would serve for the duration of the Revolutionary War and ultimately promoted to Major General in 1782. Following his tenure as senior officer, he tried his hand at farming and land speculation.

In 1785, he became the Continental States Secretary at War, then served as the 1st Secretary of State for War during Washington's first term as President. He resigned in 1794 to tend to his family and business interests. Henry Knox died in 1806, aged 56, after suffering from an infection brought on by swallowing a chicken bone.