In the 1970's, the US Army decided that it needed a self-propelled anti-aircraft gun, similar to the West German Gepard or Soviet ZSU-23-4. The result was the M247 Sergeant York.
This article describes the M247 itself, the procurement process, and all the problems that led to Caspar Weinberger describing it as "basically an ineffective system" when it was cancelled in 1985.
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