Most remarkable point of Puerto Rico 65th in Korean War is its
braveness to enable US 1st Marine Division withdrew from famous
Chosin Reservoir in dec,1950, when the Marines were encircled by
the PLA. However, the overall gloomy big retreat of the UN force
including the 1st Marine Division was started by the easily
collapse of ROK II Corp overrun by Chinese troops, that not only
made the supposed to be centered 2 US Infantry Divisions become
flank units of the whole 8th Army & X Corp, but also, The
overrun of the ROK II Corp post allowed PLA infiltrated several
regiments into the heights that overlooking the only retreat route
of the US 25th , 2nd divisions and Turkish brigades. The late fate
of these retreated units were doomed obviously, ironically, from
the size of PLA infiltrated units( several reigments), that the
force overran ROK II Corp was never big, considering ROK II Corp
was made of 4 Divisions
http://www.korean-war.com/TimeLine/1950/11-23to12-31-50.html
By shortly after midnight a confused
battle was taking place all three 2 ID regiments were engaged but
had been fragmented into company and part battalion sized units by
infiltrating Chinese and were attacking units from all directions.
Another CCF regiment infiltrated across the Ch'ongch'on River north
of Kunu-ri and attacked the two reserve battalion 23rd and the
three artillery battalions. This attack was turned but the Chinese
withdrew to a mountain known as "Chinaman's Hat", located northeast
of the 23rd but south of the rearmost positions of the 9th.
Fighting tapered off at dawn but by noon word arrived that
ROK II Corps 7th & 8th Divisions had been overrun and
ROK II Corps was retreating in mass, thus making the 2 ID not only
the flank unit for IX corps but also for Eighth Army. The route of
ROK II Corps allowed the Chinese to infiltrate several regiments
and turn them toward the mountains overlooking the road between
Kunu-ri and Sunch'on, the 2 ID & Turkish Brigades withdrawal
route. It also allowed the Chinese to attack down the road
toward Kunu-ri. To counter these incursions, the 1st Cavalry
Division moved to take up positions at Sunch'on and the road
leading east from there. The Turkish Brigade received orders to
move from Kunu-ri eastward to Tokch'on and clear the town.
Far to the west in I Corps area the 24th ID was ordered to halt its
advance and be prepared to withdraw back to the Ch'ongch'on. The
same order went out to the ROK 1st Division.