S3: What role did initiative play for UN Forces in the Pusan Perimeter and their subsequent breakout?

The Incheon landing was the initiative that was needed to breakout of the Pusan perimeter. It gave the U.S. a foothold behind enemy lines and the ability to capitalize on the foothold. It helped break the supply line even more and disrupted the NPKAs command and control. Once word spread to the NPKA that was further east, it helped demoralize them to a degree. While the NPKA commanders in the east realized that the NPKA would begin retreating they followed suit even though they were ordered not to. It gave the U.S. the ability to gain momentum and seize and hold terrain.