Historians routinely cite Dreadnought as a prime example of military revolution. But what did this revolution accomplish? Britain's
technological innovation added fuel to an existing arms race, with each of the industrialized powers--the United States not least among them--hurrying to acquire dreadnought-type warships for its own navy. Yet Dreadnought's impact on reigning concepts of sea power was negligible. If anything, the powerful new class of warship reinforced the naval orthodoxy of the day: Dreadnought seemed the ideal instrument for applying the precepts of sea power developed by the influential American naval officer and publicist Alfred Thayer Mahan, precepts derived from Mahan's study of naval history in the days of sail. In that sense, and although marking an impressive advance in naval technology, Dreadnought served primarily to affirm rather than to subvert the accepted rules of the game. Since it posed no threat to the recognized conventions of naval warfare, the revolution inspired by Dreadnought also had little impact on the definition of what constituted moral or immoral conduct when fighting at sea. From a moral perspective, it was immaterial.

In fact, however, certain of the assumptions underlying those conventions--specifically the Mahanian notion that a dominant battle
line of heavily armed surface ships offered the key to both command of the sea and world power--were shaky at best. This became apparent in 1914 when a war of epic proportions engulfed Europe.

In determining that war's outcome, the squadrons of massive dreadnoughts, built at such enormous expense, figured only marginally. In a brutal conflict that lasted over four years, the main British and German fleets met only once in battle, the inconclusive action off Jutland in 1916. For the most part, they sat out the war, warily eyeing each other from anchorages on opposite sides of the North Sea. According to Winston Churchill, the admiral commanding Britain's Grand Fleet at Scapa Flow "was the only man on
either side who could lose the war in an afternoon." Yet such a back-handed testimonial amounted to tacit acknowledgment of an
embarrassing fact that Churchill was loath to admit outright: In the vast and desperate struggle of the First World War, the military
instrument into which Britain had poured such treasure, and that epitomized the power of the Empire, remained for all practical
purposes on the sidelines. Perhaps through recklessness or miscalculation the commander of the Grand Fleet could lose the war,
but all of his mighty dreadnoughts made precious little contribution to winning it.

Having said that, to conclude from the relative inactivity of the main British and German battle fleets that maritime matters as such
were unimportant to the conduct of the war would be a great error. On the contrary, both sides understood that the ability of the Allies to sustain their armies in France hinged on the Royal Navy's control of the world's sea lanes. As has so often been the case in the history of warfare, comparative disadvantage served as spur to innovation. Overmatched in the race to build battleships, Germany was compelled to explore unorthodox ways of turning the Allies' maritime flank. This imperative gave birth to a second revolution in naval affairs: undersea warfare.

With the aim of severing the enemy's strategic lines of communications--especially Allied trade with the Americas--Germany revived and radically transformed the tradition of commerce raiding. Both Allies and neutrals such as the United States denounced the
U-boat campaign as barbaric. Certainly, in its "unrestricted" form it was ruthless. It was also highly effective--until the Royal Navy
(supported from early 1917 onward by the Americans) suspended the further construction of battlewagons and poured resources into the fledgling science of anti-submarine warfare (ASW).

Although undertaken reluctantly by the naval establishments involved, this shift in emphasis signified a transformation of naval warfare
that cut far deeper than the revolution wrought by Dreadnought. Operationally, the U-boat redefined the concept of "battle" at sea.
Strategically, it suggested ways of bringing sea power to bear more decisively than through the classic fleet actions envisioned by the
disciples of Mahan. Both of these developments also had profound moral implications. In the context of the just-war tradition,
submarine warfare posed a particular challenge to the principle of discrimination, in the narrow sense of declaring merchant ships
(often carrying non-combatants) to be fair game for unwarned attack, and in the broader sense of enticing military planners to consider the feasibility of campaigns designed to bring the enemy civilian populace slowly "to its knees."

Yet even if farther reaching than Dreadnought, the U-boat revolution was itself transitional, superseded in short order by a third even more fundamental transformation in naval affairs. This was the revolution in naval air power.

No sooner had the First World War ended than the Mahanians attempted to put the undersea genie back in the bottle. The Allies stripped the German navy of its U-boats and by treaty prohibited Germany from acquiring new ones. Old-line officers in the victorious navies scrapped their ASW fleets and directed their energies once again to perfecting the dreadnought, designing a new generation with even larger caliber guns and heavier armor. But most of this was retrograde nonsense, naval nostalgia swathed in armor plate, teak, and gunpowder.

Within the navies of the advanced nations--but especially in the navies of the United States and Imperial Japan--reform-minded officers pursued a new vision that would shatter that nostalgia, ending once and for all the battleship's reign as the standard for
measuring maritime power. Their goal was as bold as it was straightforward: to harness air power to naval power in ways that would create a sea-based weapon of unprecedented flexibility and effectiveness.

The immediate product of this vision was the aircraft carrier, wielded with spectacular success by the United States Navy in the next world war. Yet to conceive of this revolution as simply one of developing the techniques of carrier aviation is to understate its true significance. Not content with the Mahanian goal of securing "command of the sea", the architects of this revolution sought to
project naval power well beyond the confines of the sea itself. Naval air pioneers aimed to eradicate the boundary between war on land and war at sea, between the traditional role of armies on the one hand and of navies on the other. Thus, for example, having broken the back of the Imperial Navy, American naval officers at the end of the Second World War were quick to claim a share in the climactic air campaigns that pummeled the Japanese home islands and the Japanese government into submission--a mission to which U.S. Navy carrier task forces would return in subsequent conflicts in Korea and Vietnam.

Yet technological opportunity alone does not suffice to explain the resourcefulness that the United States demonstrated in seizing upon
the potential of naval air power. This was a military revolution that had economic, cultural, intellectual, and even psychological roots.
In the decades leading up to the Second World War, American society as a whole had evolved a deep-seated predisposition favoring the reliance upon air power. Moreover, the remarkable American capacity for large-scale research and production, for the diffusion of technology on a grand scale, and for what would later be called systems integration all made the United States ideally suited to
transform the airplane from newfangled contraption to pre-eminent instrument for waging war.

The moral implications of this expanded application of naval power were large. Even if not explicitly intended to terrorize civilians,
carrier-based attacks against the enemy's "vital centers" inflicted some--at times extensive--injury to civilians and damage to
non-military facilities. Whatever the intentions of planners or air crews, such collateral damage was an all but inevitable byproduct of
the large-scale use of air power from the 1940s through the 1960s. Perhaps the efforts to exploit the potential of carrier aviation to
the fullest did not foster a deliberate disregard for the claims of jus in bello. At a minimum, however, they encouraged an insensitivity
or indifference to the moral issues implicit in the freewheeling use of the air weapon. One result was the mutilation of the principle of
non-combatant immunity to the point that it became nearly unrecognizable.

Yet for all the glamor of carrier operations, the ultimate expression of the naval air revolution--and the initiative posing the largest
challenge to the just-war tradition--lay not in manned aircraft but in nuclear-tipped guided missiles. By the late 1950s, U.S.
development of the submarine-launched ballistic missile (SLBM) carried the revolution in naval air to its Cold War-driven
conclusion: holding Russian cities hostage to guarantee that the United States retained a retaliatory capability that the Soviet Union
was powerless to disarm. Beginning with Polaris--and followed later by Poseidon and Trident--the SLBM transformed the meaning of capital ship. The Polaris submarine was the first major naval combatant whose weapons were designed exclusively to attack land targets rather than ships. More importantly, it was an instrument of war explicitly intended to obliterate non-combatants on a massive scale--to go the U-boat one better and bring a nation to its knees virtually in an instant. In the logic of deterrence, the SLBM's indiscriminate destructive power was its primary military virtue. In the context of the just-war tradition, that virtue was a moral nightmare.