10. George Washington Class

By the grim logic of the Cold War, submarines armed with strategic nuclear missiles did much to keep the peace. Hidden under the ocean and extremely difficult to detect, the nuclear-powered ballistic missile submarine (SSBN) was the perfect deterrent. A potential adversary knew that even if a surprise nuclear attack wiped out land-based missiles and bombers before they were launched, the SSBNs (or "boomers") would survive to retaliate. The world’s first SSBN was the USS George Washington, first ordered in 1957 and commissioned in 1959. Earlier Soviet subs had carried nuclear-armed ballistic missiles, but they were diesel-powered boats with limited endurance. The George Washington’s nuclear propulsion enabled it to remain underwater for months without surfacing. Each of the five boats in the George Washington Class carried 16 Polaris missiles, giving a single submarine the capability to devastate an opponent’s heartland.