The increased allotment of black troops entering the corps and the commandant's call for replacing all white noncommissioned officers with blacks as quickly as they could be sufficiently trained caused problems for the black combat units. The 51st Defense Battalion in particular suffered many vicissitudes in its training and deployment. The 51st was the first black unit in the Marine Corps, a doubtful advantage considering the frequent reorganization and rapid troop turnover that proved its lot. At first the reception and training of all black inductees fell to the battalion, but in March 1943 a separate Headquarters Company, Recruit Depot Battalion, was organized at Montford Point.[4-28] Its cadre was drawn from the 51st, as (p. 109) were the noncommissioned officers and key personnel of the newly organized ammunition and depot companies and the black security detachments organized at Montford Point and assigned to the Naval Ammunition Depot, McAlester, Oklahoma, and the Philadelphia Depot of Supplies. [Footnote 4-28: Memo, CO, 51st Def Bn, for Dir, Plans and Policies, 29 Jan 43, sub: Colored Personnel, Ref Br, Hist Div, HQMC.] In effect, the 51st served as a specialist training school for the black combat units. When the second black defense battalion, the 52d, was organized in December 1943 its cadre, too, was drawn from the 51st. By the time the 51st was actually deployed, it had been reorganized several times and many of its best men had been siphoned off as leaders for new units. To compound these losses of experienced men, the battalion was constantly receiving large influxes of inexperienced and educationally deficient draftees and sometimes there was infighting among its officers.[4-29] [Footnote 4-29: For charges and countercharges on the part of the 51st's commanders, see Hq, 51st Defense Bn, "Record of Proceedings of an Investigation," 27 Jun 44; Memo, Lt Col Floyd A. Stephenson for CMC, 30 May 44, sub: Fifty-First Defense Battalion, Fleet Marine Force, with indorsements and attachments; Memo, CO, 51st Def Bn, for CMC, 20 Jul 44, sub: Combat Efficiency, Fifty-First Defense Battalion. All in Ref Br, Hist Div, HQMC.]