A woman dressed as a zombie participates in an event to promote the Spanish release of the movie “Resident Evil: The Final Chapter” in Madrid, Spain, January 28, 2017. (Photo by Susana Vera/Reuters)

Star Wars collector James Burns, 44, poses for a photograph with some of his collection in London December 2, 2015. He said “I've met so many wonderful people, all over the world. It's a wonderful community of likeminded people with an interest in Star Wars. There's nothing else like it”. (Photo by Paul Hackett/Reuters)

Throughout the course of the long war in Afghanistan, Coalition troops have relied on thousands of military working dogs to help keep them safe, and make their jobs easier. The dogs are trained to detect explosives, to find illegal drugs, to search for missing comrades, or target enemy combatants. Not only are they active on the front lines, but behind the lines they serve as therapy dogs, service dogs, and loyal companions. They also share the same risks as the ground troops, suffering injuries and sometimes death on the battlefields. Gathered here are images of these dogs and their handlers in Afghanistan and back home, from over the past several years, part of the ongoing series here on Afghanistan.

A Republican farmer defending a farm on the outskirts of Irun against Nationalist forces during the Spanish Civil War, 6th September 1936. A comrade lies dead by his side. (Photo by Keystone/Hulton Archive/Getty Images)

Students from Glasgow Art School modelling casual clothing and Buchan tartan in the annual Fashion Show for charities. During Rag Week students parade in the city streets wearing costumes designed and made by themselves. (Photo by Haywood Magee/Picture Post/Getty Images). 7th February 1953

Three Chinese soldiers at the time of a civil war in China. (Photo by General Photographic Agency/Getty Images). 1922

A model prepares backstage ahead of the Amber & Thomas show during Rosemount Australian Fashion Week Spring/Summer 2011/12 at Overseas Passenger Terminal on May 3, 2011 in Sydney, Australia. (Photo by Ryan Pierse/Getty Images)

Fascist youth, both boys and girls, in the rebel uniforms in Irun after the city had been captured by the rebels. (Photo by Maeers/Fox Photos/Getty Images). 13th November 1936