At the risk of sidetracking the thread even further... look at the Korean War Timeline:
1950
25 June North Korean People's Army crosses the 38th parallel and invades South Korea (Republic of Korea). North Korean radio proclaims that the South Korean army had tried to invade North Korea (People's Democratic Republic of Korea) and that they had been forced to invade the south.
1 Oct South Korean troops cross the 38th parallel.
1 Oct MacArthur calls upon North Korea to surrender.
1 Oct South Korean troops cross the 38th parallel.
7 Oct UN General Assembly authorizes UN forces to cross the 38th parallel.
So, about 90 days after the initial attack, UN forces are back to the "start" position.
16 Oct The chinese troops cross the Yalu and enters Korea.
21 Nov American troops reach the Yalu.
~ 6 weeks for UN troops to move from the 38th to the Yalu
26 Nov Chinese troops begin a counter-offensive.
25 Dec Chinese troops cross the 38th parallel.
~ 4 weeks for Chinese to move from Yalu to 38th
After that, it was back and forth fighting mostly around Seoul with neither side able to force a conclusion.
Casualties:
Dead/ Wounded and Missing/ Total
US estimates: 29,550/ 106.978/ 136.978
China estimates: ?/ ?/ 900,000
Once again, it comes down to will. Interesting that it all ended just where it started. Coincidence? I think not.
Clearly, the Chinese are awesome only in their willingness to accept huge losses. Otherwise, they are pretty easy to inflict huge losses upon. Even they became unwilling to tolerate the losses that they would have incurred if they had tried to conquer all of South Korea. Thus the peace agreement was finally reached.
The US/UN were/are not willing to accept continual losses. When it became clear that the war would drag on if fought above the 38th, the will to do so vanished (unlike the determination during the relatively easy drive to the Yalu after Oct. 7).
It all comes down to "will".
