Famously, the Battle of the Bulge in the winter of 1944/45 was one of the largest and bloodiest armed conflict of the Second World War. Taking place in densely forested Ardennes region between Belgium and Luxembourg, it was the last major German offensive campaign on the Western Front during World War II. Researchers have used drone-mounted LiDAR – which emits pulses of light to create 3D models and maps – to'see through' the thick forest canopy. They found nearly 1,000 features within the landscape, including dugouts, bomb craters and even artillery emplacements where troops positioned their guns. Pictured are LiDAR images from the study.

SINCE the United States military campaign began in Afghanistan, the unmanned spy plane has gone from a bit player to a starring role in Pentagon planning. Rather than the handful of ''autonomous vehicles,'' or A.V.'s, that snooped on Al Qaeda hideouts, commanders are envisioning wars involving vast robotic fleets on the ground, in the air and on the seas -- swarms of drones that will not just find their foes, but fight them, too. But such forces would need an entirely new kind of network in which to function, a wireless Internet in the sky that would let thousands of drones communicate quickly while zooming around a battle zone at speeds of up to 300 miles an hour. Such a network would have to be able to deal instantaneously with the unpredictable conditions of war and cope with big losses. Designing this network is a monumental task.