2. Spanish Armada (1588). This was the duke of Medina Sidonia's purportedly invincible fleet, ordered by Spain's King Philip II to cross the Channel and land in England. There Spanish forces would unseat England's Queen Elizabeth I. By installing a friendly regime, the expeditionary force would terminate English support for the Dutch revolt roiling the Spanish Netherlands while ending English privateering against Spanish shipping. The Catholic Philip sought and obtained papal approval for the enterprise against the Protestant Elizabeth. Weather, however, conspired with English seamanship and gunnery tactics to condemn the expedition. The Spanish host was unable to land. Instead Medina Sidonia found himself compelled to circumnavigate the British Isles under foul conditions to reach home port. The failed cross-Channel crusade heartened the English crown. Had the Armada replaced a Protestant with a Catholic monarch, it's conceivable that the British Empire never would have been founded—and certainly not in the form it actually took. How would Atlantic, Pacific, and Indian Ocean history have unfolded then? The implications of that question boggle the mind—and qualify the Armada's defeat as decisive in the largest sense.

1. Salamis (480 B.C.). Taken in tandem with its immediate precursors, the sea battle of Artemisium and the land battle at Thermopylae, the Battle of Salamis was part of a joint campaign that would gladden Corbett's heart. Themistocles, the founder of the Athenian navy, led an outnumbered, outmanned allied fleet against King Xerxes' Persian armada. Artemisium kept Persian sea forces from linking up with the colossal horde that had crossed the Hellespont and was lumbering overland through Greece, with the ultimate goal of conquering Europe. Themistocles' fleet then retired to the waters off Salamis Island to defend the Athenian populace, which had abandoned its city to the Persians. Guile and artful tactics let the allies overcome Persian numbers in this narrow sea. If not for Spartan and Athenian audacity, at sea as on shore, Xerxes may have throttled Western civilization in its infancy. Fending off the Great King's onslaught entitles Salamis to enduring fame. It was the most decisive naval battle in history.

Needless to say, drawing up a list like this one is tough. Many worthy candidates ended up on the cutting-room floor. China's Ming Dynasty was born through inland naval warfare, at the Battle of Lake Poyang (1363). The Battle of the Virginia Capes (1781) doomed Lord Cornwallis' army at Yorktown and assured American independence. The naval battles at Guadalcanal (1942-1943) reversed the tide of war in the Pacific, while the Battle of the Philippine Sea (1944) doomed Japanese naval aviation—paving the way for history's last major fleet engagement, at Leyte Gulf later that year. None, however, compares to the top five for world-historic significance.

Lastly, it's fun and enlightening to speculate about the dogs that didn't bark. About, that is, the naval engagements of immense consequence that could have, and perhaps should have, yet never did take place. For instance, the U.S. Navy just celebrated the bicentennial of the Battle of Lake Erie. Despite the dismal results of the War of 1812, small-scale engagements such as Lake Erie and the Battle of New Orleans impressed the British leadership with the United States' latent military and naval strength. Trivial-seeming U.S. victories implanted the idea among British statesmen that a conciliatory policy toward Washington was more prudent than trying to outmatch a republic predestined for primacy in North America and its marine environs.

Why the rise of America didn't produce a cataclysmic naval war with the supreme sea power of the day is worth mulling over. But that, as they say, is a story for another day.

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The age of the steel line-of-battleship really began in the 1880s, with the construction of a series of warships that could carry and independently aim heavy guns external to the hull.  In 1905, HMS Dreadnought brought together an array of innovations in shipbuilding, propulsion, and  gunnery to create a new kind of warship, one that could dominate all existing battleships.

Although eventually supplanted by the submarine and the aircraft carrier, the battleship took pride of place in the navies of the first half of the twentieth century. The mythology of of the battleship age often understates how active many of the ships were; both World War I and World War II saw numerous battleship engagements. These are the five most important battles of the dreadnought age.

Battle of Jutland:

In the years prior to World War I, Britain and Germany raced to outbuild each other, resulting in vast fleets of dreadnought battleships.  The British won the race, but not by so far that they could ignore the power of the German High Seas Fleet.  When war began, the Royal Navy collected most of its modern battleships into the Grand Fleet, based at Scapa Flow.

The High Seas Fleet and the Grand Fleet spared for nearly three years before the main event. In May 1916, Admiral Reinhard Scheer and Admiral John Jellicoe laid dueling traps; Scheer hoped to draw a portion of the Grand Fleet under the guns of the High Seas Fleet, while Jellicoe sought to bring the latter into the jaws of the former.  Both succeeded, to a point; British battlecruisers and fast battleships engaged the German line of battle, before the arrival of the whole of the Grand Fleet put German survival in jeopardy.

The two sides fought for most of an afternoon.  The Germans has sixteen dreadnought battleships, six pre-dreadnoughts, and five battlecruisers.  Against this, the British fielded twenty-eight dreadnoughts and nine battlecruisers. Jellicoe managed to trap the Germans on the wrong side of the Grand Fleet, but in a confused night action most of the German ships passed through the British line, and to safety.

Many, on both sides, considered Jutland a disappointment.  Both Scheer and Jellicoe believed that they missed a chance to destroy the enemy fleet, the latter with considerably more justifiable cause. Nevertheless, together the two sides lost four battlecruisers and a pre-dreadnought battleship.  Had either side enjoyed a bit less luck, the losses could have been much worse.

Battle of Mers-el-Kebir:

The surrender of France in 1940 left the disposition of the French Navy in question. Many of the heavy ships, mostly located in French colonies, could aid either Axis or British forces.  In early July 1940, Winston Churchill decided to take a risk averse approach.  The Royal Navy would force a French decision, with the result of either seizing or destroying the French navy.

The largest concentration of French ships, including four French battleships, lay at Mers-el-Kebir, in Algeria. Two of the French battleships were veterans of World War I; old, slow, and not particularly useful to either the Italian or the British navies. The prizes were six heavy destroyers, and the fast battleships Strasbourg and Dunkerque.  These ships could contribute on either side of the conflict.

The British dispatched Force H from Gibraltar, consisting of HMS Hood, HMS Valiant, HMS Resolution, the aircraft carrier HMS Ark Royal, and a flotilla of supporting ships to either intimidate or destroy the French.  Royal Navy representatives submitted an ultimatum to their French counterparts, demanding that the ships either join the British, sail to America and disarm, or scuttle themselves. What precisely happened in the communications between Force H and the French commander remains in dispute.  What we do know is that the British battleships opened fire, with devastating results. Bretagne’s magazine exploded, killing over a thousand French sailors.  Provence and Dunkerque both took hits, and promptly beached themselves.  Strasbourg made a daring dash for the exit, then outran Hood to escape the British task force.

In the end, the British sank one obsolete ship and damaged another.  They damaged one fast battleship, and let another escape.  1300 French sailors died during the battle. Fortunately, the surviving French sailors had little interest in serving the Germans; they would eventually scuttle most of their ships at Toulon, following a German invasion of Vichy.

Battle of Calabria:

Most of the battles in the Mediterranean theater in World War II came about as the result of convoy protection.  The Italians needed to escort their convoys to Libya, while the British needed to escort convoys to Malta, and points east.

In July 1940, shortly after the destruction of the French fleet at Mers-el-Kebir, the far escorts of two convoys met each other in battle.  An Italian task force consisting of the battleships Giulio Cesare, Conti di Cavour, and various smaller ships rubbed up against a British convoy including HMS Warspite, HMS Malaya, HMS Royal Sovereign, the aircraft carrier HMS Eagle, and associated escorts.

The Italians had the initial advantage, as the dispersal of Royal Navy ships meant that only Warspite could fire upon the Italian line.  Warspite engaged both enemy ships, coming under fire from Giulio Cesare as Malaya and Royal Sovereign hurried to her aid.  After several near misses on both sides, Warspite struck with one of the longest hits in the history of naval artillery.  The hit, which detonated ammunition on Giulio Cesare’s deck, resulted in a loss of speed that forced the Italian ship out of line.  This cost the Italians their moment of advantage; with odds at 3-1, the remaining Italian ships retired.

Although the Italians failed to score a victory in the battle, they did demonstrate that the Royal Navy could not operate in the central Mediterranean without heavy escort.  The addition of two new, modern fast battleships in the next months would give the Italians a major advantage, which the airstrike on Taranto would ameliorate only for a time. The Allies could not claim naval supremacy in the ‘Med’ until 1943, when the Italian fleet surrendered under the guns of Malta.