Answer: Still drowsy, Druse mistakes the horseman for a grand statue.
Explanation:
Carter Druse was a Union soldier who was from the Confederate state of Virginia. He had felt a strong devotion to his nation and so joined the Union. One day, after a long 36 hour march, he was placed as a sentry but the exhaustion caused him to sleep.
When he woke up he saw a man on a horse who was looking at their position. At first and for a brief moment in his drowsy state, he thought that it was a grand statue that had been made to commemorate the civil war. This feeling was dispelled by the slight movement of the horse.