Early accounts of the attack state that the defenders "failed to safeguard the perimeter" of the FSB. The only single volume study written about the attack by Keith Nolan contests this position, pointing out that "historians the author of the book, who had discussed Mary Ann in an earlier work got it wrong." Even with this new perspective, there are indications that alertness at Mary Ann was not as good as it could have been. Many accounts by men stationed at Mary Ann mention that perimeter security was uneven at best. One member of the 1/46th Infantry Headquarters Company stated that "I don't think Captain Knight commander of Charlie Company, 1/46th Infantry had a clue as to how lax the security was ... because in that area, and only that area, Knight wasn't diligent. He left it up to his lieutenants and sergeants to check the bunker line." In many cases they failed to do so, and the failure was compounded by Charlie Company being understrength and unable to man all the perimeter bunkers. Manning bunkers was not the only problem. Tripflares located in the Concertina wire around the base were not always reset or replaced when they went off, a common occurrence caused in some cases by the rotor wash created by large CH-47 Chinook helicopters bringing in supplies or backhauling material as 1/46th Infantry prepared to hand the base over to the ARVN. This lax attitude, combined with the skill of the attacking sappers, had fatal consequences for many in Charlie Company. Although not "cringing in their bunkers", the defenders of Mary Ann were not prepared for a ground attack. This lack of readiness was not noted by the 196th LIB commander, Colonel William S. Hathaway during a visit to the base on 27 March, the day before the attack. He later stated that what he'd seen at Mary Ann that day "was a big improvement over that I had seen before ... the troops were alert."