Technology undoubtedly matters, but only rarely in the sense that an isolated technological achievement lends decisive advantage in tactical engagements.
In the early 1970s, Admiral Elmo Zumwalt pushed the idea of the Sea Control Ship (SCS), a small carrier that would defend sea-lanes against long-range Soviet strike aircraft and Soviet submarines. Faced with the growing expense of modern supercarriers (the first Nimitz class carrier would enter service in just a few years) and the impending retirement of the venerable Essex class carriers, Zumwalt sought a low cost option for air operations that did not demand the full capabilities of a major carrier group. Escort carriers had helped win the Battle of the Atlantic, and Sea Control Ships might make a similar contribution in a NATO-Warsaw Pact conflict.
Weapons die for all kinds of different reasons. Sometimes they happen at the wrong time, either in the midst of defense austerity, or with the wrong constellation of personnel. Sometimes they fall victim to the byzantine bureaucracy of the Pentagon, or to turf fights between the services. And sometimes they die because they were a bad idea in the first place. For the same reasons, bad defense systems can often survive the most inept management if they fill a particular niche well enough.
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This article concentrates on five systems that died, but that might have had transformative effects if they had survived. These transformations would only rarely have changed the course of wars (countries win and lose wars for many reasons besides technology), but rather would have had ripple effects across the entire defense industrial base, altering how our military organizations approached warfighting and procurement. Not all the changes would have been for the best; sometimes programs are canceled for sound reasons.