 At 0630 on July 11 , four T @-@ 34s advanced on 3rd Battalion 's position , passing through a minefield without suffering any casualties . Following the tanks , about 1 @,@ 000 North Korean infantry of the North Korean 3rd Infantry Division conducted a double envelopment of the battalion , setting up roadblocks in its rear to prevent resupply and evacuation of wounded . Simultaneously , heavy mortar fire struck the battalion 's command post , destroying its communications center and ammunition stocks , and inflicting heavy casualties . American forward observers were unable to communicate with the artillery due to the lack of communications equipment . The attack by the North Koreans was well coordinated , and it is likely that North Korean forces driven from the position in the night had been able to gather intelligence about the battalion 's position . In the ensuing fight , American forces were overwhelmed again , fighting in desperate hand @-@ to @-@ hand combat . 
