Fleshing out personnel—against short-fuzed manpower and time factors—for the 1st Marine Division and Wing, due to embark in mid-August, a month after the brigade had left, was a round-the-clock operation for all hands. Between 25 July-5 August, the Marine Corps provided personnel for the expanded Division/Wing by:
transfer of FMFLant-selected, 2d Division/Wing air and ground units, of 6,800 men, to FMFPac;
transfer of 3,600 regular Marines from 105 posts and stations throughout the U.S.;
mobilization of 2,900 from early OMCR ground and air units; and utilization of two replacement drafts, number 900, intended for the 1st Provisional Marine Brigade.
Expansion of the 1st Marine Division was in two phases, bringing the division (less one RCT) up to war strength and then organizing its third reinforced infantry regiment, the 7th Marines. With the cadre of 3,459 men in the division after the brigade left and the influx of regulars and reservists, the 1st Division embarked for Korea between 10 and 24 August. It had reached wartime strength (less one RCT) on 15 August, just 27 days after beginning its buildup from a peacetime T/O. As it had approached war strength, the Division CG, General Smith, was directed by CMC ltr of 4 August to activate a third RCT and prepare it for departure to Korea no later than 1 September.
While mounting out, the division transferred approximately 1,000 of its rear echelon to be used in the buildup of the 7th Marines. The 6th Marines of the 2d Division provided the base for building this new regiment. (Approximately 800 Marines of 3/6 were reassigned from Mediterranean duty and ordered to the Far East, via the Suez Canal, to join the 7th Marines upon its arrival there.) By drawing men from widely scattered sources, it was possible to activate the 7th Marines on 17 August. Departure of this regiment on 1 September was thus far in advance of the late fall or winter target date originally set by the JCS.
With all OMCR ground units called up and absorbed into the 1st and 2d Divisions, and air squadrons being mobilized on a slower schedule (due to less-urgent combat needs for air personnel in the early war stage), the Marine Corps dealt with its remaining body of reserve strength. Bulk orders went out beginning 15 August to the Volunteer Reserve, and by the end of the year 58,480 men and women in this category were on active duty. More than 80 percent of the volunteer reservists on Marine Corps rolls served during the Korean War.
Attesting to the impact of events in Korea is the fact that “following the epic withdrawal of the 1st Division from the Chosin Reservoir, the number of new enlistments into the active Volunteer Reserve jumped from 877 in December to 3,477 in January.”[724]
[724] Giusti, op. cit., p. 36.
Complete mobilization of the organized ground reserve had been accomplished in just 53 days, from 20 July to 11 September. A previous estimate had shown an expected 80 percent availability of ground reserve on M-Day; the actual mobilization figure was 90 percent. Of 33,528 OMCR ordered to active duty, a total of 30,183 (1,550 officers/28,633 enlisted) reported. Marine aviation also expanded rapidly. By January 1951, 32 organized reserve air units (20 of the 30 existing VMFs and all 12 MGCIs) had been activated and by October of that year all of the reserve squadrons had been called to active duty. Of the 6,341 organized air reservists, 5,240 received orders; 4,893, or 93.4 percent, reported in. In contrast to the ground reserve, air units had been recalled on a staggered or partial mobilization schedule, a matter which was later to receive Congressional attention (and ultimately to set a new trend) when the Nation’s entire Korean War mobilization procedures were reviewed and subsequently revised.