In the Saddle by Oliver Optic

As Major Lyon rode out from the hospital he encountered Sergeant Sluder pressing his horse to the best of his speed; but it was hardly necessary for him to deliver the message of which he was the bearer, for there was movement enough among the men to assure him that the enemy were approaching, even if Artie had not seen the return of the pickets.

The major waved his handkerchief three times above his plumed hat, and the American flag came down at once on the bridge. Deck had not fallen asleep at his post, though he found the situation very monotonous. The sergeant reached the commander, and delivered a message from Captain Gordon. The major had never been in a regular battle, only in the affairs with the ruffians at Riverlawn and Lyndhall.