A U.S. Marine leads training on a shooting range in France in an undated photo taken during the First World War. (Photo by Reuters/Courtesy Library of Congress)

The second of six C-17 Globemaster III airlifters for the United Arab Emirates Air Force and Air Defence is being assembled at the Boeing assembly facility on May 10, 2011 in Long Beach, California. The UAE will take delivery of three more C-17s this year and two in 2012 as it modernizes its airlift capabilities. (Photo by Kevork Djansezian/Getty Images)

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)

146 West End Stars hold a flashmob in support of the non-profit organistation Love 146, which campaigns to end child s*x slavery and exploitation, at Trafalgar Sqaure on April 11, 2011 in London, England. (Photo by Tim Whitby/Getty Images)

Nora Muaid stands in Zawraa Park on December 2, 2011 in Baghdad, Iraq. The park's 180-foot tall Ferris wheel opened earlier this year and is the second largest in the Middle East. (Photo by Mario Tama/Getty Images)

U.S. Army soldiers from the 2-82 Field Artillery, 3rd Brigade, 1st Cavalry Division, wait to load onto their armored vehicles as they prepare to convoy to Kuwait from Camp Adder in Iraq on December 7, 2011 at Camp Adder, near Nasiriyah, Iraq. (Photo by Joe Raedle/Getty Images)

South Korean special warfare command soldiers participate in winter military training exercise on January 11, 2012 in Pyeongchang-gun, South Korea. The South Korean troops train in temperatures below -20 degrees celsius to defend the country against any possible attacks from North Korea. (Photo by Chung Sung-Jun/Getty Images)

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.