That evening Sergeant Ernest R. Kouma led the patrol of two M26 Pershing tanks and two M19 Gun Motor Carriages in Agok . Kouma placed his patrol on the west side of Agok near the Kihang ferry . At 20 : 00 a heavy fog covered the river , and at 22 : 00 mortar shells began falling on the American @-@ held side of the river . By 22 : 15 this strike intensified and North Korean mortar preparation struck A Company 's positions . American mortars and artillery began firing counterbattery . Some of the A Company men reported they heard noises on the opposite side of the river and splashes in the water .