Nothing clearly was left to him now but to remain where he was--within supporting distance, and await the issue of the fight beyond.

He was putting up his glass, when the dull boom of cannon in the extreme western limit of the horizon attracted his attention.

By the still gleaming sky he could see a long gray line stealing up from the valley from the distant rear of the headquarters to join the main column.

They were the missing supports! His heart leaped.

He held the key of the mystery now.