What the hell is Prussia?
Prussia was a Germanic empire that existed from the 1500's until the Unification of Germany in 1871. It was one of the most powerful German countries until the Unification and its capital (Berlin) became the capital of the unified German empire.
This is how Central Europe looked from 1815-1866, Prussia (marked in identified in German, 'Preußen') is dark blue (and the light blue to the east of it I think, just added later... the map says '1848-1851 zum Deutschen Bund', but not to what country)

The Battle of Prussia probably refers to fighting around Koenigsberg, today the Russian city of Kaliningrad (the original Prussian capital) and other areas of Eastern Prussia, though I can't say I've ever heard of a Battle of Prussia.
http://en.wikipedia.org/wiki/PrussiaI would have to say that the most interesting WWII battles for me are the Battles of Britain, Kursk, Stalingrad, El Alamein, and Berlin, and the Siege of Moscow.