Hooker had used spies, analysts, and even hot air balloons to compile a vast amount of intelligence about Lee’s army. He had discerned, for example, that Lee had only 61,000 men to Hooker’s own 134,000. Buoyed by his superior numbers, Hooker covertly moved 70,000 of his men fifteen miles up and across the river, and then ordered them to sneak back down to position themselves behind Lee’s army. In effect, Hooker had cut off the Confederate soldiers in front and behind. They were trapped. Satisfied with his advantage, Hooker became convinced that Lee’s only option was to retreat to Richmond, thus assuring a Union victory.