[423] CTE 90.85 constituted the MARLEX training element of TF-90, Amphibious Force Far East, redesignated Amphibious Group Western Pacific earlier that month.
Meanwhile, on 15 May, command post and subordinate units from the 1st, 5th (less RCT-5 currently deployed in MARLEX I), and 7th Marines and support elements took part in a one-day division CPX at Camp Casey stressing mobility, security and operational procedures. Another CPX on 22–23 May by 11th Marines and engineer personnel emphasized dispersion, camouflage, and message handling under simulated combat conditions. Units of the three infantry regiments plus the KMCs training with the 7th Marines at Indianhead combined in a CPX-FEX (command post-firing exercise) on 26–27 May. Realism bowed to current ordnance supply economics in that ammunition was carried for individual weapons, but it would “not be loaded except on specific orders from an officer.”[424]
[424] 1stMarDiv msg to addees in 1stMarDiv G-3 Jnl, dtd 22 May 53.
The CPX-FEX was held as a trial exercise for an Eighth Army CPX scheduled later in the month, which was postponed indefinitely on 29 May because of the critical battlefront situation and continuing enemy attacks across the EUSAK front. Extensive preparations were also underway for MARLEX II, with RCT-7, from 2–10 June; and concluding MARLEX III, scheduled 14–23 June, with RCT-1.
Armor and advance regimental elements had left for the Ascom City-Inchon staging area by 1 June, preparatory for departure to the Yongjong-ni beaches on the Korean west coast in the vicinity of Kunsan. The troop list included approximately 250 officers and 4,450 enlisted from Colonel Funk’s 7th Marines and support units, including USN and KMC. Infantry personnel from the regiment’s three battalions formed the three assault teams plus a reserve battalion composed of 475 Korean Marines designated as BLT 5/KMC. Regimental support units included Company C, 1st Engineer Battalion; Company D, 1st Medical Battalion; Company C, 1st Shore Party Battalion; Company B, 1st Armored Amphibian Battalion, and various motor transport, amphibian truck, military police, and helicopter detachments.
R-Day on 5 June went off per schedule. Despite intelligence estimates which cheerily predicted that only “nine days of rain can be expected during the month of June”,[425] RCT-7 drew one out of the barrel with its D-Day landing, 6 June. This took place during heavy rains and decreased visibility which threw the boat waves off phase by minutes and required more than the allotted time for HMR-161 troop and cargo lifts.
[425] MAR RCT LEX II, Opn Plan I, App. 1 to Annex B, dtd 9 May 53, p. 1, in 7thMar ComdD, May 53.
Use of a 144-foot-long M-2 steel treadway pontoon bridge loaned by the Army, emplaced from the end of the causeway to the beach high water mark, was considered highly successful. It solved unloading problems encountered in the earlier MARLEX, in that all heavy equipment and vehicles were landed on the designated beaches. Further experimentation with this novel employment of the M-2 was recommended to test the coupling system of bridge and causeway during periods of heavy surf. On the minus side, shore party officers noted that night transfer operations had been hindered because of the lack of running lights on the amtracs.
On 9 June, as RCT-7 was on the way back from its amphibious exercise, a directive from ComNavFE (Vice Admiral Robert P. Briscoe) notified the division of cancellation of the forthcoming RCT MARLEX III. All available shipping was being held on 24-hour readiness for the expected final repatriation of POWs (Operation BIG SWITCH). All afloat training exercises by Marine, Army, and Navy units between 6 June and 15 October were to be cancelled.
The division was host to ranking I Corps, Eighth Army, Korean, and 1st Commonwealth officials when a special helicopter assault demonstration was staged 11–12 June at Camp Casey. Two rocket launcher sections, 14 HMR-161 copters, and 2/5 infantrymen were deployed to show the diverse combat capabilities of the aerial workhorse. While in I Corps reserve, the division was also host—and winner—of the I Corps Pistol Matches. And 3/11, which the previous month had taken the Army Training Test 6-2 (a) Modified, was notified the battalion had scored 92.91 percent and received congratulations from the CGs, I Corps Artillery and Eighth Army.