The idea for this novel came from a story on the radio, a true story, which, even in blistering heat, heavily pregnant, in a traffic jam on Park Lane, sent a shiver down my spine. The programme was about the animals who’d given their lives during the Great War and was broadcast around the time that the memorial to them was erected on Park Lane. Through my car window I could see that memorial as I listened. This was the story that I heard.

During one of the war’s most horrifying battles, the German siege of Verdun, a French garrison was trapped, surrounded by enemy guns. This garrison, having run out of ammunition and food, was on the point of losing all hope when one soldier spotted something strange and dreadful racing towards them: an angel or perhaps a devil  - black, with wings, a massive head and huge, strange eyes. As the form moved closer the desperate men realized that what they were seeing was a dog and a dog they knew well, Satan, a black greyhound collie mongrel. What had appeared to be bug eyes was a gas mask, and the wings two wicker baskets on either side of his back.

Satan had almost reached his master Duvalle, when the men saw him lurch sideways and fall. The French author, Terhune, a witness, writes “A German bullet had found him. He staggered to his feet, reeling and dizzy. For an instant he seemed to have lost his way. Then he settled into that steady run again.”

British Ambulance dog. This is the postcard that, in the novel, Stanley received from Tom and has stuck to his bedroom wall.

Another bullet tore into his leg and Satan fell. Stricken, Duvalle leapt up onto the parapet, and in full view of the enemy, yelled,”Courage, mon ami! Venez pour la France.” At his master’s voice, Satan rose and struggled on, trailing a shattered limb. He arrived at Duvalle’s feet, delivered the precious missive and collapsed dead, riddled with a dozen bullets. On his collar was a message, pleading with the garrison to hold out, to wait for the relief that was being sent. On Satan’s back, in each basket, was a pigeon. The French put a duplicate message into the cylinder round the neck of each pigeon, giving details of the position of the deadly German battery and begging for it to be silenced. The pigeons were released and the French garrison watched with bated breath. One pigeon was shot down but the other flew through the gunfire and on home. In the space of minutes, shells from the French artillery poured into the German battery and silenced it.

As if this wasn’t enough to raise the hairs on one’s neck, and to send one running for one’s pen, I heard this story too.

A British Army soldier removing a message from a German Army messenger dog captured in the British lines.

An Airedale, named Jack, recruited by the British Army from the Battersea Dogs Home and trained at the War Dog School, was sent out to the Western Front. Jack’s battalion came under heavy fire. If the entire battalion was not to be wiped out, it needed reinforcements and ammunition. No human runner would survive the barrage of gunfire in order to get a message out. One Lt Hunter slipped a message into the Jack’s collar and said, “Goodbye. Jack. Go back boy. ”

Jack ran off, staying close to the ground, taking advantage of whatever cover there was, running through deep swamp for over half a mile. Under heavy bombardment he began to get hit. A piece of shrapnel smashed his jaw. The battalion watched Jack stagger on. A missile ripped open his black and tan coat from shoulder to thigh, but still he continued, using shell holes and trenches for cover. His forepaw was hit and he fell. Jack rose, dragged himself along the ground on three legs for the last few miles, persevering, inch by inch, until he reached his master and fell dead at his feet, his jaw broken , his leg splintered. Airedale Jack saved his battalion that day, and earned himself a posthumous VC.

This is a picture of a brindled Great Dane, that I kept on my desktop while writing, for the character of Bones.

Before the moment I heard these stories, I hadn’t known that there’d been seven thousand dogs killed in the Great War. I hadn’t known that they’d served as sentinels, scouts, sentries, ambulance and messenger dogs. I heard stories of other animals, there on Park Lane, but it was the idea of the messenger dog, of his intelligence, loyalty and of the sense of duty that could draw a dog through gunfire, back to his master, that brought tears to my eyes.

The dog in my story is a messenger dog like Satan and Airedale Jack, trained to carry messages back to his master. Like Airedale Jack, he is an English dog, though, like Satan, he has the speed of a greyhound and the intelligence of the Collie. All of the events in his life are drawn from the lives of dogs that served on the Western Front.

Messenger dogs and their handlers marching to the Front, in France, during World War I. Straining at the leash, these messenger dogs and their keepers are apparently on their way to the front line trenches.

A portrait of 3133 Corporal James Coull, with dogs of No. 3 Messenger Dog Section, attached to the 4th Divisional Signal Company, in a railway cutting near Villers-Bretonneux while operating with 12th Brigade. A Messenger Dog Section comprised sixteen men and fifty messenger dogs.

Left to right we see War Dog 103 Nell, a Cross Setter; 102 Trick, a Collie; 101 Buller (sometimes referred to as Bullet), an Airedale. All three dogs were very efficient in message carrying and saw service with the 2nd, 4th and 5th Australian Divisions, also with Divisions of the British 8th Corps (Imperial). 102 Trick was particularly efficient and was specially mentioned by his Signal Officer for good work at Rubimont, near Heilly.

A pillbox known as Anzac Strong Post, was captured by Australian troops in the attack of the 1st and 2nd Australian Divisions, on 20 September 1917. They hoisted an Australian flag just as an enemy messenger dog arrived at the post, carrying messages for a German officer, telling of the Australian attack and instructing him to hold out at all costs. The dog was killed by shellfire later in the day, and the flag was destroyed, for the pillbox suffered many direct hits from the enemy's high explosive shells. This photograph was taken a week later. Note the ANZAC sign and the rifles leaning against the pill box.

St. Gratien, France, 1918. Members of the 2nd Divisional Signals Company, 1st AIF, with the unit's messenger dogs, in an area northeast of Amiens.

Bandaged dog that worked in the front line trenches, in France, during World War I. With bandages on all four paws, this dog - called 'Paddy' - carried out a range of hazardous duties in a front line trench, despite the shellfire and poison gas. Photographer Tom Aiken

Messenger dog Bruce, a well known Collie who was always working under shell fire in the line, with its handler, in France, during World War I. T A scrolled up message can be seen attached to the dog’s collar. Photographer Tom Aiken

Messenger dogs and their handlers stand beside some kennels close to the front line. Photographer Tom Aiken

Messenger dog bounding across shell holes on its way to headquarters, in France, during World War I.

Messenger dog bringing a message to soldiers in a shell hole in France, during World War I. A dog-handler unfastens his collar so as to read the message that has been sent to his unit. Photographer Tom Aiken

A Messenger dog paddles across a canal to reach its handler, in France, during World War I. Photographer Tom Aiken

With his soaking wet messenger beside him, this handler is checking a message that this dog has just carried to him. It is likely that the kit bag worn on the handler’s chest would have contained the incoming and outgoing messages. Photographer Tom Aiken

British messenger dogs with their handler, France, during World War I. Usually the dogs were strays, before being rounded up by the Army. Generally, however, traditional working breeds, such as collies, retrievers, or large terriers, were chosen for messenger work. Messenger dogs were based in sectional kennels near the front lines. On average each sectional kennel had 48 dogs and 16 handlers, a ratio that indicates how important the dogs' work was at the front.

British soldier with messenger Dog

Dog leaping gate (training)

Messenger dogs and handlers in trench

A messenger dog running past an explosion in a field

Dogs passing a barricade of rifle fire during training

Dogs in training leaping a fence