I've seen the quote "Generals are always prepared to fight the last war" be attributed to Winston Churchill by several sources, but none of them actually give a primary source (such as a transcript of one of Churchill's speeches, a passage from one of his books, et cetera) to support this attribution.
Using Google Ngram, I've found that using the phrase "fighting the last war" in this context became popular for the first time around 1940, specifically as an explanation of the defeat of the Allied forces in the Low Countries and France against Germany that year. It's therefore not implausible that Churchill would have used it at some point, but I simply can't find any evidence of him ever doing so.
I think it's quite unlikely Churchill actually coined the phrase, but regardless, I'm interested in two questions: did this phrase actually originate with Churchill, and if it didn't, is it nevertheless possible to attribute the quote in the title to him?