Relief of the 25th Infantry Division by Marine units got underway on 6 July when the first incoming elements of Colonel Funk’s 7th Marines moved up to the right regimental sector manned jointly by the U.S. 14th Infantry Regiment and the Turkish Armed Forces Command. Advance personnel reported into the left sector, to be taken over by the Marine 1st Battalion, and at 1400 the 3d Battalion relieved the TAFC reserve battalion in the rear area.
Two platoons from the Marine regiment’s 4.2-inch Mortar Company, meanwhile, also began their phased relief of the Turkish Heavy Mortar Company. The incoming mortar crews had some unexpected early target practice. As the men took up their active MLR firing positions in the right battalion sector, they were promptly forced to put their tubes into action to silence a troublesome machine gun, enemy mortars, and hostile troops behind the Jersey Ridge to the north and Reno and Elko on the west. That evening the 2d Battalion opened its new command post in the eastern sector, occupied by two TAFC battalions.
Sharply at 0455 on 7 July, the 7th Marines assumed responsibility for the right regimental sector and came under operational control of the 25th Division. Shortly after noon that day, forward units of 1/7 reached the 25th Division sector after a three hour motor march from Camp Indianhead, through driving rains in their second day without letup. At the battalion sector, 1/7 joined the advance echelon of 40 men who had arrived the previous day and took over its MLR positions from the 14th Infantry. Additional 7th Marines units reporting in throughout the day and assuming new locations were the weapons, mortar, and antitank companies.
The first of Colonel Tschirgi’s 5th Marines returned to their center regimental sector before dawn that same day to begin their relief of the Army 35th Infantry Regiment. At 0300 the 3d Battalion assumed responsibility for the eastern half of the MLR. By late afternoon, antitank personnel and the 2d Battalion were in line, the latter taking over the western battalion sector at 1716. In the rear regimental area, early elements of Colonel Nelson’s 1st Marines, locating just south of the Imjin River, had begun to arrive by 1300. The regiment would assume ground security for the Spoonbill and Libby (formerly X-Ray) bridges in the sector as well as MASRT #1.
No one needed to remind the 1st Marine Division that the territory it was moving back into was not the same—with respect to defense posts in the right regimental sector—that it had left two months earlier. Three of its six outposts there (Carson, Elko, Vegas) had fallen to the enemy in the late-May battle, despite the formidable resistance of the defending Turks. Outpost Ava remained at the far western end of the line, with the Berlin-East Berlin complex in the right battalion area. Some 6,750 yards of intervening MLR—more than four miles—lay in between, bereft of any protective outposts to screen and alert the defending line companies to sudden enemy assaults. The Marines were thus returning to a main line of resistance considerably weakened in its right regimental sector.
As the 1st Division CG, General Pate, observed:
Vegas [had] dominated the enemy approaches to Berlin from the north and northwest and therefore made Berlin relatively secure. Berlin, in turn, dominated the enemy approaches from the north and northwest to East Berlin and made East Berlin relatively secure. The loss of Outpost Vegas to the CCF placed Berlin and East Berlin in very precarious positions and negated their being supported by ground fire except from the MLR.[483]
[483] CG, 1stMarDiv, Berlin Rpt., p. 1.
Ground support fire from the MLR, moreover, tended to be only moderately successful in supporting the outposts because of the nature of the terrain. A major Communist stronghold, Hill 190, lay northeast of the Carson-Elko-Vegas complex. Since Berlin (COP 19) and East Berlin (COP 19-A) were sited on extensions of this same hill mass, the enemy could make sudden “ridgeline” attacks against the Berlins. With buffer outpost Vegas now lost, the likelihood of CCF success in such attacks was “immeasurably increased.”[484]
[484] Ibid., p. 2.