Good points. There is no way to be certain what has accounted for peace in Europe it's more than likely a combination of things. It's my opinion Nuclear armament played a role. I say that because WW1 was supposed to be the war to end all wars because casualties were on such an unprecedented level, but less than a generation later, WW2 popped off again. After WW2, there were two factions in Europe(NATO and Soviet Union) and both were nuclear powers so I think that went far in promoting peace.
Surely, the spread of Soviet Sphere of influence wouldn't have went unanswered by other European powers if the Soviet Union was not a nuclear power.
I don't deny that nuclear firepower played a role in that peace simply that history shows that if it did, it did so by playing a minor role when comparing to European countries realizing they needed to build together and the fact they hadn't any sufficient force/hate left to do otherwise anyway. Also, thanks to the Marshall Plan, economy of European countries aligned to the West boomed and Europeans didn't really care about warring with each other when money and consumption were sky high.
WW1 was supposed to be the last, you're right but that was from the mouth of the victors. The Versailles treaty was never digested by the Germans (they didn't even sign it if I recall and called it a "diktat") because it was too humiliating. It built frustration in the German side and bring defiance on all of the Germans who supported it (communists, Jews...) which increased their desire to revenge and mixed with the rising antisemitism in Europe, the nazism in Germany, Hitler's charisma and plenty other things, it was a bomb ready to explode, which it did obviously. So yeah, the WWI casualties should have been enough to bring peace to Europe but it would have been that way if the Versailles treaty was at least fair. Which it wasn't.
When people talk about the importance of nukes as a peace keeping strategy in the 20th century (at least in Europe, I don't know how it is in the US), it's more to refer to the Cold War than WW2. Hiroshima was the US giving Japan an honorable way to surrender, Nagasaki was the US flexing to the Soviet Union and a complete and unnecessary act of terror : none of those nukes were about peace but about power.
Europe started developing nuclear weapons on behalf of the USA to oppose the Soviets' rise. If you look at the numbers, the USA and Russia hold like more than 90% of all nukes on earth while the USA was the first country to have and Russia a close second. No European countries ever threaten another European country with nukes (from my memory). Unlike Russia and the USA.
If you're interested, here's a pretty clear link about the whole thing :
http://www.heritage.org/research/re...in-europe-critical-for-transatlantic-security
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