This event has always bothered me, and partly illustrates why there were such high casualties among Machine Gunners. The squad had been informed by local citizens that a party of North Koreans had been seen entering this tunnel, so the Marines were only making sure they had gone on through.

Still, the M1919A4 Light Machine Gun although slightly off-set from the tunnel axis, is vulnerable to whatever firepower the enemy left to delay pursuit. The Marine throwing a grenade into the entrance should have thrown a WP grenade in first, before any troops exposed themselves to fire from within.