An attempt to move the 25th Infantry Division's division trains through the valley became mired in the mud through the night of August 10–11 and was attacked in the morning by KPA forces who had driven American forces from the high ground. In the confusion, KPA armor was able to penetrate roadblocks and assault the supporting US artillery positions. The surprise attack was successful in wiping out most of the 555th and 90th Field Artillery Battalions, with much of their equipment. Both KPA and American armor swarmed to the scene and US Marine aircraft continued to provide cover, but neither side was able to make appreciable gains despite inflicting massive numbers of casualties on one another. Upon later inspection, the bodies of 75 men, 55 from the 555th Field Artillery and 20 from the 90th Field Artillery, were found executed when the area again came under American control. "Task Force Kean" was forced to withdraw back to Masan, unable to hold its gains, and by August 14 it was in approximately the same position it had been in when it started the offensive.