Charles L. Holbrook became Colonel on Aug. 31, 1850, and continued in command until Aug. 15, 1854; William Schouler, destined to be the great Civil War Adjutant General of Massachusetts, was Lieutenant Colonel. To Col. Holbrook fell the painful duty of marshalling his regiment against the mob on June 2, 1854, at the time of the Burns riot. In that year the organization consisted of eight companies. To him also fell the more congenial privilege, in Oct., 1862, of leading his command, the same regiment but then known as the 43d Mass. Vols., during its campaign in North Carolina. Col. Holbrook was, in civil life, a bookkeeper, first in the Suffolk National Bank, and subsequently in the Custom House; as a soldier he jumped from the Adjutant’s office to the Colonelcy. Owing to the formation of new companies it became desirable to organize an additional battalion of infantry in 1853, to which the number 3d was given. This included Capt. Poore’s National Guards as Co. A, the Union Guards of East Boston, organized in 1852, as Co. B, and the Sarsfield Guards as Co. C, all under command of Maj. Robert I. Burbank. Col. Thomas E. Chickering commanded the 1st Regiment from Oct. 25, 1854, until Jan. 29, 1856; and during his administration the name of the organization was changed from Light Infantry to “Infantry.” Col. Chickering commanded the 41st Mass. Inf., which became the 3d Cavalry, 1862-1865, and served in the department of the Gulf, transferring to Gen. P. H. Sheridan in Virginia during 1864. In 1855 the 3d Battalion of Infantry disbanded, the National and Union Guards going into the 2d Regiment as 9th and 6th Cos. respectively, while the Sarsfield Guards passed out of existence. The transfer of two strong companies to the 2d was a sign that the latter regiment was increasing while the 1st decreased. Six years later the 2d was to receive the much-desired number which had thitherto belonged to the “1st.” Maj. Joseph Bradley had become commander of the 3d Battalion at the time of its disbanding.