The US began its participation in the Korean War with a goal of saving South Korea from being conquered by Communist forces. In September 1950 the US adopted a much more ambitious goal, conquering North Korea and uniting the Korean peninsula under anti-Communist rule. The US achieved the first goal but not the second. It would be perfectly reasonable to define "victory" in terms of the first goal, and say the US won the war. It would be equally reasonable to define "victory" in terms of the second, and say that the US did not win the war.
Stephen, the idea of World War I as a pyrrhic victory is well established, especially vis-à-vis France, by scholars like Bob Doughty.
World War I could probably counted as such in more ways than one. Germany defeats Russia in 1917-1918, only to lose the war altogether a few months later. The Entente victory over Germany in 1918 seems to mostly pave the way for World War II.
A brief reply like this is hardly adequate to discuss the weighty question of what constitutes victory or defeat. But I'd like to comment only on your statement "sometimes the cup of defeat is not so empty and bitter after all (the defeat of Egypt in 1973 for example)."
Wouldn't the apparent victory of the US in the Cold War be an instance of a victory that wasn't quite as glorious as it first looked?
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