The United States Department of Defense (DoD) was originally named the War Department in 1789. The current organization founded by Congress in 1947 is based in the Pentagon in Arlington County, Virginia near Washington DC.
Army, Air Force, Coast Guard, Navy, Marines and agencies such as the National Security Agency comprise the Department. Its annual budget is roughly $280 billion (~$1,000 per capita). Web site at http://www.defenselink.mil/
As part of the September 11, 2001 Terrorist Attack, a terrorist crashed a plane into one of the sections of the Pentagon, causing part of it to collapse and killing about 190 people.
The DoD sponsored the research and development of the modern computer and through DARPA subsidized the creation of the Internet. It maintains a network of global positioning satellites (GPS). Each of these technologies was made available to the public worldwide at no charge.