The boat-load of prisoners, about to be exchanged and returned to their own army, were allowed to pass through a busy port of military embarkation and debarkation, with every opportunity to observe everything that was going on, and, to make a bad matter worse, the steamboat captain was himself a Confederate sympathizer. So when Mosby, from the exchange boat, observed a number of transports lying at anchor, he had no trouble at all in learning that they carried Burnside's men, newly brought north from the Carolinas. With the help of the steamboat captain, Mosby was able to learn that the transports were bound for Acquia Creek, on the Potomac; that meant that the re-enforcements were for Pope. * * * * * As soon as he was exchanged, Mosby made all haste for Lee's headquarters to report what he had discovered. Lee, remembering Mosby as the man who had scouted ahead of Stuart's Ride Around MacClellan, knew that he had a hot bit of information from a credible source. A dispatch rider was started off at once for Jackson, and Jackson struck Pope at Cedar Mountain before he could be re-enforced. Mosby returned to Stuart's headquarters, losing no time in promoting a pair of .44's to replace the ones lost when captured, and found his stock with Stuart at an all-time high as a result of his recent feat of espionage while in the hands of the enemy. So he was with Stuart when Stuart stopped at Laura Ratcliffe's home, and was on hand when Stuart wanted to make one of his characteristic gestures of gallantry. And so he finally got his independent command--all of six men--and orders to operate in the enemy's rear. Whatever Stuart might have had in mind in leaving him behind "to look after the loyal Confederate people," John Mosby had no intention of posting himself in Laura Ratcliffe's front yard as a guard of honor. He had a theory of guerrilla warfare which he wanted to test. In part, it derived from his experiences in the Shenandoah Valley and in Fairfax County, but in larger part, it was based upon his own understanding of the fundamental nature of war.