Obviously the gap of 80 miles separating the Eighth Army from X Corps would have to be reduced before much help could be given by the latter. General Almond replied to General Wright in a letter proposing that X Corps attack to the west of the Chosin Reservoir while also continuing to advance northward in zone to complete its original mission.
That same day, while the letter was en route to Tokyo, General MacArthur came to a far-reaching decision. In a radio message he directed the X Corps commander to develop, as an alternative to OpnO 6, a plan for reorienting his attack to the west on reaching Changjin in order to cut the Chinese MSR, as represented by the Manpojin-Kanggye-Huichon road and rail line.
This was the first indicated change in mission, according to the X Corps command report, since CinCFE’s directive late in October calling for a drive to the border. The amendment “was made necessary,” the report continued, “by the enemy build-up in front of the Eighth Army and the fact that the enemy action had halted the first attempt ... to advance Eighth Army to the border. An estimate of the Eighth Army situation ... fixed the relative combat power as 100,000 UN to 100,000 enemy with UN forces having air superiority and superior artillery support.... The enemy was given an offensive capacity which he could implement with an estimated reserve of 140,000 CCF troops north of the Yalu River. In view of the enemy’s offensive capacity, Eighth Army adopted a conservative plan to make a general advance with the main effort in the center generally parallel to the enemy MSR (Huichon-Kanggye). This course of action was designed to meet any course of action which might be adopted by the enemy. To assist the Eighth Army advance, X Corps was to initiate a main attack to the West from the Chosin Reservoir area, cutting the enemy MSR at Mupyong-ni, and advance in a northwesterly direction to the Yalu River line at Manpojin.”[326]
By a coincidence it was also on Wednesday, 15 November, that General Smith wrote a letter which foreshadowed future military events. Addressed to General Clifton B. Cates, Commandant of the Marine Corps, this communication made it plain that the 1st Marine Division commander and his staff did not share in the renewed optimism as to the course of the UN war effort. Not only did the Marines accept the possibility of imminent and formidable CCF intervention, but they were making preparations to meet it.