Greg forgot.

As he darted through the doorway to the porch overlooking the area he found Corporal Brayton's gaze fastened upon him in severe displeasure.
"Mr.Holmes, button your coat, sir!" Reddening and frowning, too, it must be admitted, Greg obeyed.
"All candidates will pass quickly through the north sally port and make formation," continued the cadet corporal.
Here the entire uniformed cadet corps was forming, facing the plain.

At the extreme left of the line a cadet lieutenant, two sergeants and four cadet corporals busied themselves with forming the candidates and alternates in line.

When the word was given the cadet corps wheeled to the right and marched off in column of fours, quite a splendid model of military precision.
Somehow the un-uniformed greenhorns managed to turn into column of fours, though some of the bewildered boys forgot to which four they belonged and there was some confusion.
Behind the superb cadet corps, toiled along these all but hopeless candidates and alternates, scores and scores of them--every fellow of them feeling more awkward than his nearest neighbors in the line.

Badly out of step was this green material.