The sentry pacing on headquarters post swung his rifle from shoulder arms down to port arms, then came to present arms before the officers, who acknowledged his formal courtesy by bringing their hands up smartly to the brims of their campaign hats.
"Well, that's over!" announced Cartwright, in a tone of relief.
"And will never be repeated," said Greg.
"But you will admit, Holmes, that you've picked a good deal on me, from time to time," Cartwright pressed, in a half-aggrieved tone.
"I will admit, for you both," smiled Dick, "that you're in danger of starting something all over again unless you shut up and make a fresh, better start.

So we won't refer to personal matters again, but we come to your company's barracks first, Cartwright, and when we get there we will shake hands and agree to remember that we're all engaged in a fierce effort to make the Ninety-ninth the best American regiment." In silence the three pursued their way to C company's building.
Here they halted.
"To the Ninety-ninth, best of 'em all," proposed Prescott, holding out his hand to Cartwright, who took and pressed it.
"To the best officers' crowd in the service," quoth Greg.
"Amen to that!" assented Cartwright, though he strode away with a dull red flush burning on either cheek.
Half an hour later Dick's business took him past the regiment's guard-house.

As carpenters were everywhere busy in camp putting up more necessary buildings the place officially known as the guard-house was more of a bullpen.

Posts had been driven deeply in the form of a rectangle, and on these barbed wire had been laid to a height of nine feet.

Within the rectangle guard-house prisoners could take the air, retiring to either of two tents inside the enclosure whenever they wished.
As he passed Dick noted, vaguely, that four or five men stood by the nearer line of barbed wire fence.