“Stacked Supercell with Lightning”. This huge mesocyclone supercell was near the Nebraska / Kansas border on the night of June 22nd, 2012. What a stunning structure! (Photo and caption by Jennifer Brindley/National Geographic Traveler Photo Contest)

ATTENTION! All pictures are presented in high resolution. To see Hi-Res images – just TWICE click on any picture. In other words, click small picture – opens the BIG picture. Click BIG picture – opens VERY BIG picture.

Apollo 9 Command/Service Modules (CSM) nicknamed “Gumdrop” and Lunar Module (LM), nicknamed “Spider” are shown docked together as Command Module pilot David R. Scott stands in the open hatch. Astronaut Russell L. Schweickart, Lunar Module pilot, took this photograph of Scott during his EVA as he stood on the porch outside the Lunar Module. Apollo 9 was an Earth orbital mission designed to test docking procedures between the CSM and LM as well as test fly the Lunar Module in the relative safe confines of Earth orbit. (Photo by NASA)

An artist's impression of a growing supermassive black hole located in the early Universe is seen in this NASA handout illustration released on June 15, 2011. Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-Ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies. (Photo by Reuters/NASA/Chandra X-Ray Observatory/A.Hobart)

Elaine Vandiver shares a moment with a two-year old alpaca as they touch noses as she washes him at her farm at 1560 Stateline Road Monday, May 11, 2015, in Walla Walla, Wash. (Photo by Michael Lopez/Walla Walla Union-Bulletin via AP Photo)

Actress Michelle Rodriguez attends the Shane Black 9th annual Hallowen party held on October 31, 2003 in Hancock Park, Los Angeles. (Photo by Frazer Harrison/Getty Images)

Sixty-eight year old cross-country runner Rosie Swale-Pope is interviewed while sitting in her cart, “The Icebird”, in Upperville, Virginia March 13, 2015. Swale-Pope, who is from Great Britain and once ran an unsupported 20,000 mile run around the globe, is currently running across the United States from New York City to San Francisco in support of cancer research. (Photo by Gary Cameron/Reuters)

The British rock and roll group the Beatles talk to Ed Sullivan at CBS Studio 50 before their live television appearance on “The Ed Sullivan Show” in New York, February 10, 1964. From left to right are, Sullivan, John Lennon, Ringo Starr, holding a cigarette, and Paul McCartney. (Photo by AP Photo)

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.