All dogs find it hard to resist the mysterious lure of a walk in human companionship.  True, the night was not an ideal one for a ramble, and the fog had a way of congealing wetly on Bruce’s shaggy coat.  Still, a damp coat was not enough of a discomfort to offset the joy of a stroll with his friends.  So Bruce had followed the twelve men quietly into No Man’s Land, falling decorously into step behind Mahan.

It had not been much of a walk, for speed or for fun.  For the humans went ridiculously slowly, and had an eccentric way of bunching together, every now and again, and then of stringing out into a shambling line.  Still, it was a walk, and therefore better than loafing behind in the trenches.  And Bruce had kept his noiseless place at the Sergeant’s heels.

Then—­long before Mahan heard the approaching tramp of feet—­ Bruce caught not only the sound but the scent of the German platoon.  The scent at once told him that the strangers were not of his own army.  A German soldier and an American soldier—­ because of their difference in diet as well as for certain other and more cogent reasons—­have by no means the same odor, to a collie’s trained scent, nor to that of other breeds of war-dogs.  Official records of dog-sentinels prove that.

Aliens were nearing Bruce’s friends.  And the dog’s ruff began to stand up.  But Mahan and the rest seemed in no way concerned in spirit thereby—­though, to the dog’s understanding, they must surely be aware of the approach.  So Bruce gave no further sign of displeasure.  He was out for a walk, as a guest.  He was not on sentry-duty.

But when the nearest German was almost upon them, and all twelve Americans dropped to the ground, the collie became interested once more.  A German stepped on the hand of one of his newest friends.  And the friend yelled in pain.  Whereat the German made as if to strike the stepped-on man.

This was quite enough for loyal Bruce.  Without so much as a growl of warning, he jumped at the offender.

Dog and man tumbled earthward together.  Then after an instant of flurry and noise, Bruce felt Mahan’s fingers on his shoulder and heard the stark appeal of Mahan’s whispered voice.  Instantly the dog was a professional soldier once more—­alertly obedient and resourceful.

“Catch hold my left arm, Lieutenant!” Mahan was exhorting.  “Close up, there, boys—­every man’s hand grabbing tight to the shoulder of the man on his left!  Pass the word.  And you, Missouri, hang onto the Lieutenant!  Quick, there!  And tread soft and tread fast, and don’t let go, whatever happens!  Not a sound out of any one!  I’m leading the way.  And Bruce is going to lead me.”

There was a scurrying scramble as the men groped for one another.  Mahan tightened his hold on Bruce’s mane.

“Bruce!” he said, very low, but with a strength of appeal that was not lost on the listening dog.  “Bruce!  Camp!  Back to camp!  And keep quiet!  Back to camp, boy!  Camp!”