The remaining seven companies were organized at Camp Stanton in Lynnfield, Massachusetts and mustered into service from August 20 to 22.

[1] After two months garrison duty in Baltimore, the regiment embarked for Louisiana, being assigned to the Army of the Gulf which was commanded by Major General Nathaniel P. Banks.

After the surrender of Port Hudson on July 9, the regiment participated in the ill-fated Red River Campaign.

They served guard duty in various locations during the spring of 1865 including Morehead City and Goldsboro.

The rest were shipped home and the 38th Massachusetts was mustered out of service on Gallops Island in Boston Harbor on July 13, 1865.