The 43rd Regiment of Foot was one of the units that marched from Boston through Lexington to Concord on April 19, 1775. The 43rd suffered both captures and casualties that morning, particularly on the retreat from Concord, and this musket was likely retrieved from one of those soldiers. It bears internal assembly marks, crown property and proof marks, company and rack numbers that place it with this light infantry unit. It was given to Captain Parker in recognition of his leadership at the historic standoff at Lexington earlier that day, during which the colonies suffered the first casualties of the War for Independence.
On January 26, 1861 both Parker muskets were accepted for the Commonwealth by Governor John A. Andrew and via joint convention were transferred to the Senate, where they have hung together in the Senate ever since.