For two hours after he had been left at his lonely post that Saturday night he stood stock-still, leaning against the trunk of a large tree, staring into the darkness in his front and trying to recognize known objects; for he had been posted at the same spot during the day.  But all was now different; he saw nothing in detail, but only groups of things, whose shapes, not observed when there was something more of them to observe, were now unfamiliar.  They seemed not to have been there before.  A landscape that is all trees and undergrowth, moreover, lacks definition, is confused and without accentuated points upon which attention can gain a foothold.  Add the gloom of a moonless night, and something more than great natural intelligence and a city education is required to preserve one’s knowledge of direction.  And that is how it occurred that Private Grayrock, after vigilantly watching the spaces in his front and then imprudently executing a circumspection of his whole dimly visible environment (silently walking around his tree to accomplish it) lost his bearings and seriously impaired his usefulness as a sentinel.  Lost at his post—­unable to say in which direction to look for an enemy’s approach, and in which lay the sleeping camp for whose security he was accountable with his life—­conscious, too, of many another awkward feature of the situation and of considerations affecting his own safety, Private Grayrock was profoundly disquieted.  Nor was he given time to recover his tranquillity, for almost at the moment that he realized his awkward predicament he heard a stir of leaves and a snap of fallen twigs, and turning with a stilled heart in the direction whence it came, saw in the gloom the indistinct outlines of a human figure.

“Halt!” shouted Private Grayrock, peremptorily as in duty bound, backing up the command with the sharp metallic snap of his cocking rifle—­“who goes there?”

There was no answer; at least there was an instant’s hesitation, and the answer, if it came, was lost in the report of the sentinel’s rifle.  In the silence of the night and the forest the sound was deafening, and hardly had it died away when it was repeated by the pieces of the pickets to right and left, a sympathetic fusillade.  For two hours every unconverted civilian of them had been evolving enemies from his imagination, and peopling the woods in his front with them, and Grayrock’s shot had started the whole encroaching host into visible existence.  Having fired, all retreated, breathless, to the reserves—­all but Grayrock, who did not know in what direction to retreat.  When, no enemy appearing, the roused camp two miles away had undressed and got itself into bed again, and the picket line was cautiously re-established, he was discovered bravely holding his ground, and was complimented by the officer of the guard as the one soldier of that devoted band who could rightly be considered the moral equivalent of that uncommon unit of value, “a whoop in hell.”