Middlesex Light Artillery was organized as an infantry company in May 1861. It served as Company K (1st) in the 47th Regiment, then became Company B of the 55th Regiment. During February 1862, it was transferred to the artillery. The unit served with the Army of Northern Virginia until after the Maryland Campaign, then in October disbanded. The men transferred to the Ashland Light Artillery and Jackson's Flying Artillery. It was commanded by Captain William C. Fleet.