D Troop of the 10th Cavalry Regiment was detached and moved around before settling in with the 3rd Infantry Division, 3rd Brigade. On 25 June 1958, D Troop was reconstituted in the Regular Army and redesignated as Headquarters and Headquarters Troop, 4th Reconnaissance Squadron, 10th Cavalry Regiment. On 1 September 1963, the unit was redesignated as Troop D, 10th Cavalry and assigned to Fort Knox, Kentucky, and on 15 April 1968 the Troop became part of the 5th Battalion, 33rd Armor Regiment of the 194th Armored Brigade. In October 1999, the 3rd Infantry Division  began its transition to Limited Conversion Division XXI . Under this force structure, mechanized brigades received organic cavalry organizations. On 16 June 2000, D Troop, 10th Cavalry Regiment was reactivated and assigned to the 3rd Brigade, 3rd Infantry Division , at Fort Benning, Georgia. In March 2003 the 3rd Brigade participated along with the rest of the 3rd Infantry Division  in the initial operations against Iraq as part of Operation Iraqi Freedom. The 3rd Infantry Division returned to Georgia in late 2003. In mid-2004 it began the transformation to the US Army's new modular force structure, which saw D Troop, 10th Cavalry inactivated.
Question: when 1958, D Troop was reconstituted in the Regular Army and redesignated as Headquarters and Headquarters Troop?
Answer: 1 September 1963