The lads of the South, where the cities were few and small, had been used from childhood to the horse.

They had become at once cavalry of the highest order; but the lads of the North were learning, too.

He had no doubt that bands of Northern horsemen were now ranging the country to the very verge of the camps of Jackson and Lee.
The belief became a certainty when a score of riders in blue appeared on a hill behind him.

One of their number blew a musical note on a trumpet, and then all of them, with a shout, urged their horses in pursuit of Harry, who felt as if it were for all the world a fox chase, with himself as the fox.
He knew that his danger was great, but he resolved to triumph over it.
He must get through to Jackson with the news that the Army of the Potomac was in Virginia.

Others from Sherburne's troop might arrive with the same news, but he did not know it.