What is the context for Patton's "We fought the wrong enemy"?

by Marvynwillames

It's a famous and polemic quote, but I've never seen the context, to who and why he said it?

HistoricalGrounds

From this post 4 years ago /u/Praporshchik gives this summary in addressing the quotation, and in his comment as well the reply below it they clarify that the quote in question comes from Patton’s diaries.