Behind Enemy Lines is part memoir, part history, and part anthropology. In the darkest days of World War 2, with Nazi Germany and Imperial Japan on the march everywhere, President Roosevelt ordered the creation of the OSS, a worldwide intelligence agency and guerilla warfare bureau under the legendary "Wild Bill" Donovan. Their first mission was the Burma theater, unwanted stepchild of the war, yet a vital link to China and defense for India.

The small OSS team, Detachment 101 (named as such because 'hell, we can't let the Brits know we only have one unit') had the good fortune to meet the Kachin people of the Burmese highlands. In their initial invasion, the Japanese had treated the Kachin with exceptional brutality, massacring and mutilating entire villages. Whether this was due to the IJA's own cruelty or bad advice from local Shan allies, the Japanese made mortal enemies of an entire people. Kachin warriors needed no training in jungle warfare. They could march miles across some of the worst terrain in the world, living off of grubs and fruits, and leaving no trace as they moved. All they needed were guns, radios, and a handful of experts in industrial warfare, and they would make the Japanese bleed.

Part of this book is a conventional military history, Unit X marched to Y and attacked. The better part is a memoir, as Dunlop was one of these OSS agents, and managed to get the tales of many of the other Detachment 101 men. He has high regard for the Kachin, a little less for the OSS, much less for the British, and no regard at all for the Chinese. What comes through, again and again, is a sincerely love of the Kachin, their courage, and their skill living in the jungle.