A thing that surprised me back when was that Germany and Italy are relatively new countries.
I also learned that Swedes and Danes still don't like each other.
This "late to the scene" issue massively contributed to both World Wars in the 20th Century. The history of how Germany was formed is a long and complicated one but the short version is that up until Napoleon they had been a collection of minor "kingdoms" or "duchys" that were at least nominally independent but frequently allied together into larger groups out of necessity. Thus the Hanseatic League and the Holy Roman Empire.
The Holy Roman Empire was famously neither holy nor roman nor an empire. Rather, it was a loose alliance of minor Germanic kingdoms and it was nearly always dominated by the Austrians.
As Prussia grew in size and power there came to be a conflict between two most powerful Germanic kingdoms, Prussia in the north and and Austria in the south. Adding fuel to the fire of this conflict was the fact that most northern Germans were Protestant Lutherans while most Southern Germans were Catholics. Prussia and Austria fought a war in 1866. This war was right after the American Civil War which ended in 1865 and just before the Franco-Prussian War of 1870. The fact that it came before the Franco-Prussian war is not coincidental. Bismark HAD to secure his southern flank before he could take on France. Then he goaded the famous Napoleon's nephew into declaring war on Prussia and promptly kicked the living crap out of the French.
The German empire was declared IN France at the conclusion of the Franco-Prussian War. Then, finally, the bulk of the German people were united into one nation but there were two major problems that would cause issues going forward:
- Most of the rest of the European peoples had already formed nation states years earlier. England, France, and Russia had existed for centuries by the time Wilhelm I was crowned Emperor of Germany. Thus, those other nations had already had the opportunity to lay claim to border areas and to acquire foreign colonies while Germany had not.
- The German people still were not actually united anywhere near to the degree that the English, French, and Russians were. Austria was still independent of Germany as part of the Austro-Hungarian Empire and there were also a lot of ethnically German people living in other parts of the Austro-Hungarian Empire outside of Austria and in areas even beyond the Austro-Hungarian Empire.
The established powers (England, France, Russia) formed an alliance to maintain their power and the less established powers of Germany and Italy formed their own alliance. The Austro-Hungarian Empire was more-or-less forced into the German/Italian camp because the established powers saw them for the fading military power that they were and weren't really interested in allying with them. The Germany-Austria-Italy alliance, however, was always tenuous at best. Italy and Austria had territorial disputes all along their border most notably South Tyrol and Trieste and there were always a large number of people in the German Empire who wanted to unite all Germans into ONE Germany. This, of course, was problematic for the Hapsburgs as they ruled a substantial number of Ethnic Germans in Austria and beyond. Worse for the Hapsburgs, there were a lot of German people within their own lands who felt more loyalty to their Germanic cousins in the German Empire than to their own perceived foreign rulers. One example of this is a certain Austrian who joined not he Austrian but the German Army in WWI, rose to Corporal, and later became infamous.
When WWI came, the Italians bowed out and eventually joined the other side through a treaty that looks more like a Real Estate Contract because it was. The British and French wanted to endanger the Southern flank of the Austrians and they traded land to Italy to accomplish that goal.
Interestingly, when the Austro-Hungarian Empire was collapsing the Germanic portions of it declared their independence as the "Republic of German Austria" with the stated goal of merging with Germany. Ie, Anschluss wasn't something that Hitler dreamed up on his own, it had been the express goal of Austria as formed. Additionally, the Republic of German Austria also claimed all of the German Speaking areas of the old empire which included a number of areas that would become problematic a quarter century later when the Nazi's claimed them.
