The European Union creates an allied front against outside aggression.There are still many problems with division in Europe despite the EU.
Explanation:
The past 50 years in Europe have been some of the most peaceful out of the last 1,000 years of history. There have been fewer wars fought on the continent then at any time since the reign of the Roman Empire over the region. The European Union creates stability because all of the nations belonging to the agreement (or NATO) work together for their mutual good. Although this does increase their operating costs because there are domestic and international governments which require funding, it makes everyone safer as well.
There are fewer countries going to war with each other in Europe thanks to the presence of the EU, but that has not stopped a rise of nationalism, fascism, and other problematic government structures over the years. There are many different cultures and ethnicities on the continent which see things differently, and it is not always possible to reconcile their differences. Not only is there a clear divide between the east and the west, but there are divisions of size to consider as well.
Many countries choose to use the strategy of appeasement against Hitler's Germany mainly because they were still recovering from World War I and wanted to resist war if at all possible. They also though Hitler was bluffing.
