The attack was initially successful because of the inexperience and poor positioning of McClernand's troops and a flanking attack from the Confederate cavalry under Forrest. The Union brigades of Cols. Richard Oglesby and John McArthur were hit hardest; they withdrew in a generally orderly manner to the rear for regrouping and resupply. Around 8:00 a.m. McClernand sent a message requesting assistance from Lew Wallace, but Wallace had no orders from Grant, who was still absent, to respond to an attack on a fellow officer and declined the initial request. Wallace, who was hesitant to disobey orders, sent an aide to Grant's headquarters for further instructions. In the meantime, McClernand's ammunition was running out, but his withdrawal was not yet a rout. (The army of former quartermaster Ulysses S. Grant had not yet learned to organize reserve ammunition and supplies near the frontline brigades.) A second messenger arrived at Wallace's camp in tears, crying, "Our right flank is turned! ... The whole army is in danger!" This time Wallace sent a brigade, under Col. Charles Cruft, to aid McClernand. Cruft's brigade was sent in to replace Oglesby's and McArthur's brigades, but when they realized they had run into Pillow's Confederates and were being flanked, they too began to fall back.