Companies began assembling at Camp Edwin M. Stanton in Boxford on during the second week of September 1862. The final of the ten companies was mustered into federal service on September 30. Carlos P. Messer, a veteran of the 5th Massachusetts who had commanded a company during the Battle of Bull Run was appointed as colonel and commanding officer. The regiment was issued smoothbore Springfield Model 1842 muskets rather than the more common, and more accurate, Springfield Model 1861 rifled musket. The soldiers of the regiment were somewhat dissatisfied with the older model weapons which were of little use at long range. However, the fact that the regiment was armed with these weapons kept them out of the worst of the fighting during the June 14 assault at Port Hudson as they were used as support troops rather than being part of the advanced assault.