The question of German unity is always a good rabbit hole to go down!

While the actual German empire was only around 50 years old at the time, the idea of a unified German speaking world was not. The roots of pan-Germanism go back to at least the time of the Napoleonic wars 100 years before WWI. The Napoleonic wars forced the small Germanic states of the former Holy Roman Empire to work together against the French, which in turn began to create a special bond between those German speaking people. After the Napoleonic wars ended in 1816 there were around 30 German states; this is down from well over 300 in the Holy Roman Empire!

So people started to ask stuff like "what is a German really?", "We just fought Napoleon together and we speak very similarly. Are we kin?", and most importantly "what will the region look like post-Napoleon and post-Holy Roman Empire?". So really, Napoleon's campaign against the HRE ended up dissolving that bureaucratic mess and unifying a bunch of tiny little Germanies.

Around the year 1820, the pan-Germanism movement is beginning to roll. A writer names August von Kotzebue wrote and criticized German nationalist movements, and was killed by a German nationalist that year. The German Confederation forms and it's a loose association of those 30 or so German countries. There's a revolution in 1848, the German Confederation splits and you get the North German Confederation, Bavaria, and a few other little Germanies. This whole time, people are asking themselves, "Austrians speak German and all that jazz. Do they count as German?" The war in 1871 solidifies the fact that Austrians will not join the German Empire, but make no mistake. This was purely political. Prussia would have lost power within the imperial parliament, and would've had to share it with Austria. So in 1871 you finally get a fully unified German state that is a distinctly different entity from Austria. It's been a full 55 years in the making, at least.

So by 1918 the German empire had existed for 47 years; the idea of a unified German speaking state in Europe had existed for about 105. Dividing Germany after that point would have been short lived because the modern German state was built on their shared experiences, and by this point they had both those experiences and precedent for a unified Germany.

The answer to your other question is much easier. After WWI, German soldiers returned home. Lots of them kept their guns and uniforms because there wasn't really much of any authority to give them back to. Many of these men joined various Freikorps, which were paramilitary groups of specific regions and specific political persuasions. This is why until 1923 there are lots of small uprisings in Germany where these Freikorps try to firmly establish power in their respective areas. These men were WWI veterans, and they had their guns, their helmets, surplus war supplies, and in some cases even machine guns. There were multiple large shootouts in Berlin between the Freikorps and the police, other paramilitary groups, or actual military. At least one Freikorps did try to declare a Bavarian Soviet Republic, aka Communist Bavaria.

In fact, in the wake of WWI, Austria voted to join Germany, but was not allowed to do so because of treaty restrictions.

Tl;dr- they could've been split up, but the sentiment was already there and the precedent of a single Germany was as well. It wouldn't have lasted long. Lots of little revolutions did happen until about 1923, during which some paramilitary groups tried to establish regional control and autonomy. Some tried to establish national control. Austria wanted to join Germany, but was told no.

Sources: William W. Hagen, German History in Modern Times: Four Lives of a Nation basically the entire first half. The second half is the interwar period and the cold war.

Barbara Jelavich, Modern Austria: Empire and Republic 1815-1986

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!