From Foreign Policy:
Dogs have been fighting alongside U.S. soldiers for more than 100 years, seeing combat in the Civil War and World War I. But their service was informal; only in 1942 were canines officially inducted into the U.S. Army. Today, they're a central part of U.S. efforts in Iraq and Afghanistan -- as of early 2010 the U.S. Army had 2,800 active-duty dogs deployed (the largest canine contingent in the world). And these numbers will continue to grow as these dogs become an ever-more-vital military asset.
These repros do not come close to doing the actual photos justice. Do yourself a favor and check out the full photo essay at the link provided above.