he state of Hesse was dominated by more than one state since the division of the estate in 1567 until the Second World War.
After 1806 Hesse-Kassel remained a landgraviate with an elector as sovereign. In 1816, the former prince-bishopric Fulda came to the county of Hesse-Kassel as Grand Duchy of Fulda. 1806, the county Hesse-Darmstadt was upgraded to the Grand Duchy of Hesse in the Rhine Confederation and got larger areas of the Principality of Mainz.
After the Prussian-Austrian War of 1866, Prussia incorporated the Landgraviate of Hesse-Kassel. By succession in 1890 Nassau came to the Grand Duchy of Luxembourg. Grand Duchy of Hesse-Darmstadt remained, but had to accept areas of Prussia, such as the county of Hesse Homburg. The free city of Frankfurt / Main was one of the conquests of Prussia.
From these newly conquered areas and two small Bavarian border areas became 1866 the Prussian province Hessen Nassau.