Adhering to his belief in the paramount importance of firepower, Mosby saw to it that none of his men carried fewer than two revolvers, and the great majority carried four, one pair on the belt and another on the saddle. Some extremists even carried a third pair down their boot-tops, giving them thirty-six shots without reloading. Nor did he underestimate the power of mobility. Each man had his string of horses, kept where they could be picked up at need. Unlike the regular cavalryman with his one mount, a Mosby man had only to drop an exhausted animal at one of these private remount stations and change his saddle to a fresh one. As a result of these two practices, Union combat reports throughout the war consistently credited Mosby with from three to five times his actual strength. In time, the entire economy of Mosby's Confederacy came to be geared to Mosby's operations, just as the inhabitants of seventeenth century Tortugas or Port Royal depended for their livelihood on the loot of the buccaneers. The Mosby man who lived with some farmer's family paid for his lodging with gifts of foodstuffs and blankets looted from the enemy. There was always a brisk trade in captured U. S. Army horses and mules. And there was a steady flow of United States currency into the section, so that in time Confederate money was driven out of circulation in a sort of reversal of Gresham's law. Every prisoner taken reasonably close to Army pay day could be counted on for a few dollars, and in each company there would be some lucky or skillful gambler who would have a fairly sizeable roll of greenbacks. And, of course, there was the sutler, the real prize catch; any Mosby man would pass up a general in order to capture a sutler. And Northern-manufactured goods filtered south by the wagonload. Many of the Mosby men wore Confederate uniforms that had been tailored for them in Baltimore and even in Washington and run through the Union lines. By mid-June, Lee's invasion of Pennsylvania had begun and the countryside along Bull Run Mountain and the Blue Ridge exploded into a series of cavalry actions as the Confederate Army moved north along the Union right. Mosby kept his little force out of the main fighting, hacking away at the Union troops from behind and confusing their combat intelligence with reports of Rebel cavalry appearing where none ought to be. In the midst of this work, he took time out to dash across into Fairfax County with sixty men, shooting up a wagon train, burning wagons, and carrying off prisoners and mules, the latter being turned over to haul Lee's invasion transport. After the two armies had passed over the Potomac, he gathered his force and launched an invasion of Pennsylvania on his own, getting as far as Mercersburg and bringing home a drove of over 200 beef cattle.