Hence, a chance bark, rising through the night to where some enemy airman soared with engines turned off, might well lead to the bombing of hitherto unlocated trenches or detachment-camps.  For this and divers other reasons, the first lesson taught to arriving wardogs was to abstain from barking.

The dogs were divided, roughly, by breeds, as regarded the line of training assigned to them.  The collies were taught courier-work.  The Airedales, too,—­hideous, cruel, snake-headed,—­were used as couriers, as well as to bear Red Cross supplies and to hunt for the wounded.  The gaunt and wolflike police dogs were pressed into the two latter tasks, and were taught listening-post duty.  And so on through all available breeds,—­including the stolidly wise Old English sheepdogs who were to prove invaluable in finding and succoring and reporting the wounded,—­down to the humble terriers and mongrels who were taught to rid trenches of vermin.

Everywhere was quiet efficiency and tirelessly patient and skillful work on the part of the trainers.  For Britain’s best dog men had been recruited for service here.  On the perfection of their charges’ training might depend the fate of many thousand gallant soldiers.  Wherefore, the training was perfect.

Hundreds of dogs proved stupid or unreliable or gun-shy or too easily confused in moments of stress.  These were weeded out, continually, and shipped back to the masters who had proffered them.

Others developed with amazing speed and cleverness, grasping their profession as could few human soldiers.  And Bruce, lonely and heartsore, yet throwing himself into his labors with all the zest of the best thoroughbred type,—­was one of this group.

His early teachings now stood him in good stead.  What once had been a jolly game, for his own amusement and that of the Mistress and the Master, was now his life-work.  Steadily his trainer wrought over him, bringing out latent abilities that would have dumfounded his earliest teachers, steadying and directing the gayly dashing intelligence; upbuilding and rounding out all his native gifts.

A dog of Bruce’s rare type made up to the trainers for the dullness of their average pupils.  He learned with bewildering ease.  He never forgot a lesson once taught.

No, the Mistress need not have interceded to save him from beating.  As soon would an impresario think of thrashing Caruso or Paderewski as would Bruce’s glum Scottish trainer have laid whip to this best pupil of his.  Life was bare and strict for Bruce.  But life was never unkind to him, in these first months of exile from The Place.  And, bit by bit, he began to take a joy in his work.

Not for a day,—­perhaps not for an hour, did the big collie forget the home of his babyhood or those he had delighted to worship, there.  And the look of sadness in his dark eyes became a settled aspect.  Yet, here, there was much to interest and to excite him.  And he grew to look forward with pleasure to his daily lessons.