1. Sea Power

The era of Sea Power was one of great transition for military naval vessels. It began with the soaring majesty of HMS Victory at the 1805 Battle of Trafalgar, and ended in the late 19th century with the forbidding armored bulk of HMS Warrior, precursor of the modern battleship. In just 50 years, sails gave way to steam. Oak hulls to iron plates. Fixed cannons to smaller, more accurate gun batteries with greater range and flexibility. The rules of naval warfare would never be the same.

2. Submarines

They have been called the ultimate warship. The epitome of stealth. Today's submarines have come a long way from the submersible oak barrel that kicked off submarine warfare in 1776. Nuclear subs can remain underwater indefinitely and destroy targets thousands of miles away. Their strategic value is immense: ballistic-missile submarines account for half of U.S. nuclear defense capabilities. No modern military power could claim superpower status without these ships, nor prevail against challenges to its might.

4. Aircraft Carriers

How does a modern navy project its power around the world? With nuclear-powered ships carrying fighter planes. Once flight became a proven asset in warfare, the aircraft carrier's importance as a naval war machine was confirmed. The aircraft carrier is now one of the U.S. Navy's most important strategic vessels. These massive, floating airbases intimidate wherever they roam.