 On August 20 , the North Korean commands distributed operations orders to their subordinate units . The North Koreans called for a simultaneous five @-@ prong attack against the UN lines . These attacks would overwhelm the UN defenders and allow the North Koreans to break through the lines in at least one place to force the UN forces back . Five battle groupings were ordered . The center attack called for the NK 9th Division , NK 4th Division , NK 2nd Division , and NK 10th Division break through the US 2nd Infantry Division at the Naktong Bulge to Miryang and Yongsan . 
