[1] With the dissolution of the Confederation and the Austro-Prussian War, control of the fortress first passed to Prussia, and, after the 1871 Unification of Germany, to the German Empire.

At the Congress of Vienna, Mainz was assigned to the Louis, Grand-Duke of Hesse-Darmstadt, but it was decided that, as a fortress, it should belong to the German Confederation, with a garrison of Austrian, Prussian, and Hessian troops.

The military governor, who retained his post five years, was alternately an Austrian and a Prussian general.

About a mile above the junction of the two rivers was the village of Kostheim on the Main, and a little farther up a bridge of boats, defended by a strong tête-de-pont.

[2] Karl Baedeker writing in 1864 stated that Mainz was amongst the strongest fortresses of the German Confederation.