American Military History, Volume 1

By the end of 1848 the Army had reverted to a peacetime strength somewhat smaller than the 10,000 authorized in 1815. It was stretched very thin by its manifold duties on the vast new frontier. On the recommendations of General Scott and Secretary of War George W. Crawford, Congress in June 1850 approved enlarging the companies serving on the frontier to 74 privates, a considerable increase over the 50 in the dragoons, 64 in the mounted rifles, and 42 in the artillery and infantry authorized at the end of 1848. Thereafter 90 of the 158 companies were enlarged; by the end of 1850 the Army was authorized 12,927 officers and men.

When Jefferson Davis became Secretary of War in 1853, he strongly urged a larger Army, one that could expand to 27,818 men in time of war by enlarging the company to 128 men. Davis desired new mounted regiments for frontier service, because only highly mobile units could hope to handle the Indians. In March 1855 Congress added 4 new regiments to the existing 15 (2 of dragoons, 1 of mounted rifles, 4 of artillery, and 8 of infantry). They were the 1st and 2d Cavalry Regiments and the 9th and 10th Infantry Regiments. The mounted arm thus consisted of dragoons, mounted rifles, and cavalry until the Civil War, when all mounted regiments were called cavalry.