The attack against the B-TOC was made easier by Lt. Col. Doyle's failure to post armed guards at the bunker's entrances (which was a violation of brigade policy), preventing any early warning. The sappers used a combination of CS gas and satchel charges in their attack on the bunker (coming at about 02:44 - the time is known because a radio operator in the bunker reported it to the FDC as direct mortar hits and the time was logged), effectively disrupting the command structure on the firebase. At about the same time, the radio operator requested illumination rounds from supporting artillery batteries, but did not indicate that Mary Ann was under ground attack. The south end of the B-TOC was burning by this time, the fire started by a satchel charge igniting a case of white phosphorus grenades located near the south bunker entrance.