My imagination took fire at the picture his few words had sketched. A train surprised by a handful of bold men in the heart of the enemy's territory; the passengers and train hands forced to get out under threat of instant death, and possibly a desperate fight before this was accomplished; then the wires cut, so that no lightning message could be flashed ahead; the secret confederate--whom there might be a show of compelling by force to mount the engine--set to his work; the train rushing on its way through a hostile country, past the towns and camps of the enemy, but rendered secure by the two elements of surprise and speed; the great bridges (like those at Green and Stone Rivers and other places, which had cost us weary delays and hard work in repairing),--all these bursting into flames as they were passed, and possibly other damage done before the daring adventurers returned in triumph to our own lines. I knew enough of war to understand, at a glance, the great military importance of thus severing railroad communications, for had I not seen our whole division brought to a halt, and General Mitchel rendered almost furious with impatience over a single burnt bridge? Besides, it required no particular insight to reveal the immense moral effect upon an enemy of such a bold stroke far in the centre of his territory. It would tend to diffuse distrust and fear through all the rebel armies if they were thus made to feel that no place in their whole country was safe from the presence and the blows of a daring adversary. "Well, what do you think of it?" said Mitchel, as he saw my preoccupation. "Why, it is the grandest thing I ever heard of!" was my enthusiastic reply. "I wish I was with them. But do you think that spy can be trusted? Spies are all the time betraying the confidence of one party or the other, and if he should be false to us, he has the lives of our boys in his hands. I have heard that he has been over the lines several times, and if he has been a secret rebel all the while, it would be a nice stroke of business for him to lead down a party of our best men and deliver them to the rebels."