Those who forget the lessons of history are doomed to repeat it. However, it depends what lessons you take from it - that Germans are evil, or that civilised countries can behave in very uncivilised ways when conditions encourage it? The latter IMO. There's plenty of xenophobia, disablism and other nastiness around in this very country in this very century. How many of the skinheads with Union Jack painted faces and a can of (quite possibly German!) lager in hand, raucously singing "Two world wars and one World Cup", hold as offensive views as any Nazi, and indeed would have been first in line to join the Hitler Youth if they'd happened to be born a few hundred miles away and a few decades ago? Most, I betcha. Bigots are always with us, and, sadly, sometimes they end up forming a government and leading a nation into all sorts of trouble with inflammatory rhetoric. UKIP
International relations ebb and flow, and one may point out that in all the wars we've had anything to do with in nearly 70 years, not to mention the humanitarian efforts, along with numerous treaties and trade agreements, our erstwhile enemies have been on the same side, pulling enthusiastically, for the most part, in more or less the same direction. They may be our enemies again some time in the future. Or they may pull us out of the shit dumped on us by some other nation we currently count as an ally. Who can tell?
ps My dad had a German surname, though he and his numerous siblings were all born in England to an English mother and joined the British forces, during WW2 or shortly afterwards. He knew about 3 short phrases in German. When my mother announced her engagement an aunt said gravely, "But my dear, he's German". My mother shot back promptly "so's the King". Aunt subsided with a shocked murmur of "You can't say things like that!"