When you mess around with German history (the stuff before WW II).....you end up with this topic of Grand Duchy. If you sit and try to get a normal German to explain this....they just look at you and note that they got rid of the Kaiser in 1919, and it's all been thrilling ever since. More or less....few know or understand the Grand Duchy term or what it involves.
So, a simplified explanation.
Going back into the 1500s, the Grand Duchy status was invented. A guy, his army and local people of importance....designed the Grand Duchy as a 'kingdom'. The neat thing about a Grand Duchy is that it's not run by emperors or kings. Yeah, that's attractive to most regions because you avoid all that royal stuff, along with the taxation it usually involves.
A Grand Duchy was run by a Grand Duke....or a prince.
It was a status that was dissolving by the end of the 1700s....then Napoleon's era helped to bring it back. Areas taken over by Napoleon's army....would turn various regions into Grand Duchy operations....to benefit those who were cooperative and helpful. Here in Germany....after 1815 and the defeat of Napoleon, the status grew more popular.
All total, in this period of the 1800s....there were sixteen authentic Grand Duchy regions (note: some are German or Prussian related, and some fall into French, Italian or Poland related):
1. The Grand Duchy of Tuscany (1569–1860)
2. The Grand Duchy of Berg (1806–1813)
3. The Grand Duchy of Würzburg (1806–1814)
4. The Grand Duchy of Baden (1806–1918)
5. The Grand Duchy of Hesse (1806–1918)
6. The Grand Duchy of Fulda (1816–1866)
7. The Grand Duchy of Finland (1809–1917)
8. The Grand Duchy of Frankfurt (1810–1813)
9. The Grand Duchy of the Lower Rhine (1815–1822)
10. The Grand Duchy of Luxembourg (since 1815 and still a Grand Duchy today)
11. The Grand Duchy of Mecklenburg-Schwerin (1815–1918)
12. The Grand Duchy of Mecklenburg-Strelitz (1815–1918)
13 The Grand Duchy of Posen (1815–1848)
14. The Grand Duchy of Saxe-Weimar-Eisenach (1815–1918)
15. The Grand Duchy of Oldenburg (1829–1918)
16. The Grand Duchy of Cracow (1846–1918)
Hessen or Nassau? Well....after 1871, the area was forced into Prussia. The Duke was nullified and zero'ed out. On the paperwork, they can claim some status of existence as a Grand Duchy until the end of WW I, but there was no Grand Duke running the show.
What all this tends to show.....is a significant number of small communities what is Germany or part of Europe today.....which were smaller in scale and controlling their own destiny. People were proud of the status of belonging to a Grand Duchy, and they tended to stay out of wars.
If the Grand Duchy design had survived on? Without the Napoleonic wars and the growth of Prussian dominance....these sixteen Grand Duchy situations would likely all have survived on. The Grand Duchy of Hesse, without WW I or WW II....would likely be one of the richest communities in Europe today.