Valiant Hearts: Dogs of War is an mobile-exclusive interactive comic that was released for iOS on November 06 2014 and Android on November 25th 2014. Players of Valiant Hearts on iOS received it as an automatic update, while Android players received it directly with the new Android launch.
The comic details Walt's life prior to the events in the Valiant Hearts game, before and after the beginning of the war. It also introduces Walt's sister, Cassie the messenger dog, and Walt's handler, Dr Hans Weiss, who appears briefly in the Valiant Hearts game.
The end of the story takes place on February 22, 1915, which places it shortly before Walt meets Emile in the Valiant Hearts game timeline.
Note: this section contains spoilers for the Dogs of War comic.
The story opens in 1911, with an introduction to Walt and his sister Cassie, who were raised by a doberman breeder, Anton, on a farm near Cologne. In 1913, both of the dogs displayed quick thinking when they helped to save a soldier from drowning in a river near Anton's farm. They made friends with Hans, the doctor who was on the scene to attend to the man. And because of their heroism, Walt and Cassie were sent into military service.
In the army, Walt was trained as a casualty dog, and Cassie was trained as a messenger. At the outbreak of the war in 1914, Hans was called to serve as a medic, and upon reaching the camp reunited with Walt and Cassie. Two months later, when Hans received his orders, Walt was the dog assigned as his casualty assistant.
After that point, Walt and Cassie were separated, and did not meet again until many months later, under heavy fire. Cassie was hit by artillery shell and was mortally wounded. Walt rushed to her, ripping from Hans's grip. While Walt looked upon Cassie's wounded form, Hans found a British soldier in the dirt. he took the soldier and prepared to leave. Walt and Hans looked at each other, realizing there was nothing they could do for Cassie. They left Cassie's body as they walked into the sunset