It's difficult to know if it's been the reason. Chances are that there wouldn't have been any wars without the EC/EU anyway. Not sure Ireland vs. UK is a great

It's difficult to know if it's been the reason. Chances are that there wouldn't have been any wars without the EC/EU anyway. Not sure Ireland vs. UK is a great example BTW. And your example with Denmark and Sweden is particularly off-base since war between these has been unthinkable for over 200 years[1] -- much longer than the EC/EU has existed. Also, Sweden joined the EU in 1995, more than 20 years after Denmark did. [1]: and it could be argued it goes back longer than that because the last clash was forced by their respective allies in the Napoleonic Wars, but neither Denmark nor Sweden actually did want to fight each other at all.