The Nike Ajax was the U.S.’s first operational surface-to-air guided missile system.
In the waning years of World War II, advances in German jet aircraft, along with global improvements in the altitude at which bombers could fly, made it obvious that antiaircraft artillery was nearing the end of its useful life. So in February of 1945, the U.S. Army launched a feasibility study to determine if a “major caliber anti-aircraft rocket torpedo” could be built. By the summer of that year, the study came back with a “yes” and the Nike program (named after the Greek goddess of victory) was started to create a line-of-sight missile system.
Since this technology was a huge leap over its predecessors, and developed in a hurry (out of concern for the threat posed by the Soviet Union’s bomber force), a number of problems had to be overcome in a fairly chaotic development. Originally, the Nike Ajax system had the liquid-fueled interceptor surrounded by eight solid rocket boosters. When by 1948 it became obvious that this configuration posed reliability problems, the strap-on boosters were replaced by a single solid rocket booster stage — which had originally been developed for a Navy anti-aircraft program. In 1951, all the pieces finally came together, and tests began of the final full-up Nike Ajax system — missile, fire control radars, and ground-based guidance computer. By 1953 the system was operational, and within just a few years hundreds of Nike Ajax batteries were stationed around major U.S. cities and military installations. But technology moves on, of course, and so during the early- and mid-1960’s the Nike Ajax systems were replaced with more capable Nike Hercules batteries. The last Nike Ajax system in the U.S. was deactivated in 1963, although the missiles continued serving overseas for some years later.
The Nike program used a nomenclature system unlike what was used on many subsequent programs. Rather than being the names of the first and second stages of the missile, Nike Ajax was the first (operational) variant of the Nike system. The second was called Nike Hercules, and the third Nike Zeus (although, just to confuse things, there were also systems dubbed Improved Nike Hercules, and Nike Zeus A and B).
Ultimately the last of the Nikes were decommissioned in the 1970’s — primarily because they had become anti-ballistic missiles (ABMs) and so were covered by strategic arms limitation treaties, but also because their anti-aircraft role had been taken over by missiles carried by manned aircraft.