Shelby sent a brigade under Colonel Sidney D. Jackman to secure his wagon trains, but these had already been removed by order of General Price. Jackman was instead intercepted by General Fagan, who alerted him to the massed Union cavalry (Pleasonton's) which had just crossed the Big Blue River to the east. Seeing Pleasanton's close proximity to the Confederate flank and rear, General Curtis had ordered a general advance of the entire Union line, with Blair's and Jennison's brigades leading the charge. Shelby, meanwhile, had only Thompson's Iron Brigade to hold off this massive assault. When one of Pleasonton's batteries arrived in support of Curtis's men, Thompson's Confederates finally broke and fled.