Prussia

Prussia is a (★★★) nation with a medium difficulty and it only appears in A.D 1865.

A.D 1865
Prussia sides with the monarch states so its allies are the German Confederation, Bavaria, the United Kingdom, Spain, Romania, Bulgaria and the Ottoman Empire. Its generals are Otto von Bismarck (Infantry), Max von Hausen (Infantry), Alexander von Kluck (Cavalry) and Roon (Artillery) Prussia borders Denmark, the Netherlands, German Confederation, Austrian Empire and the Russian Empire. Prussia should try to wipe out Denmark and Austria as they're your biggest threats but keep in mind of Russia who can attack you if the border between the two nations are left unguarded.