September 29, 2009:
In the last century, each war has left pretty clear signs about which new weapons and gear will be common in future ones. This is all about the rapid increase in the speed with which new technology is developed. Thus in World War I we saw the early use of aircraft, armored vehicles, assault rifles, body armor, electronics and the blitzkrieg (high-speed combat tactics with massive armies). In World War II we first saw wire-guided missiles, smart bombs, electronic warfare, tank gun stabilization, smart mines, homing torpedoes, jet aircraft, ballistic missiles, cruise missiles and a lot of other stuff that did not really mature until several decades after 1945.
What are we seeing now? Lots more personal electronics for infantry, armed battlefield robots, the beginning of the battlefield Internet, and a lot more sensors. There are already portable electronic devices that can see through walls. There's more pattern recognition software that can examine digital video and make decisions on what is dangerous, and what is not. In the lab, there is a "crowd scanner" that examines how flushed (excited, as in blood rushing to different parts of their faces) people are, and who might be feeling guilty, or ready to attack. The last decade has seen the first large scale use of combat robots (if you don't count naval mines, which were first introduced in the late 19th century.)
Now you know what kind of weapons will be common, reliable and most effective in a decade or two.