The 4th Cavalry Regiment is a United States Army cavalry regiment, whose lineage is traced back to the mid-19th century. It was one of the most effective units of the Army against American Indians on the Texas frontier. Today, the regiment exists as separate squadrons within the U.S. Army. Presently, 1st Squadron, 4th Cavalry and 5th Squadron, 4th Cavalry are parts of the 1st Infantry Division's 1st Brigade and 2nd Brigade combat teams, respectively. 1st Squadron, 4th Cavalry's official nickname is "Quarterhorse", which alludes to its "1/4 Cav" designation.The 3rd Squadron, 4th Cavalry, official nicknamed "Raiders," serves as part of the 25th Infantry Division. The 4th Squadron, 4th Cavalry officially was stood up on September 2009 at Fort Riley, Kansas as part of 1st Infantry Division. It was inactivated in October 2015. The 6th Squadron, 4th Cavalry served as part of the recently inactivated 3rd Brigade Combat Team, 1st Infantry Division, at Fort Knox, Kentucky.