You MUST have other examples of your "greatness", don't you?
X th century - conflict over Pomerania between Mieszko I, the ruler of Poland and Margrave Hodo of the Nordmark Northern March and Saxon March, who was also ruler of the neighbouring marchy of Lusatia. Germans were beaten and forced to withdrawn.
XI th century - 1003 - 1018 war between polish king Bolesław the Brave and German Henry II the Holy Roman Emperor - Germans lost Lusatia and Misnia.
XII th century - in 1109 Henry V, German Holy Roman Emperor, invades Poland but in short time is beaten and forced to withdrawn.
XV th century - The Great War (1409-1411) between Kingdom of Poland / Grand Duchy of Lithuania and Teutonic Knights. The result - Poles won and the power of Teutonic Knight’s was broken.
The Thirteen Years' War 1454-1466 - between Kingdom of Poland and Teutonic knights - Poles won. As a result Prussia as a whole was incorporated into the Polish kingdom; the Teutons were allowed to rule only its eastern part as Polish vassals.
XVIth century - 1519-1521 - war between Teutonic knights and Kingdom of Poland - Poles won. Result - the end of existence of Teutonic Knights.
Not bad, innit? :)
Actually, Bratwurst Boy, Germans were never strong enough to destroy Poland completely. The only reason Poland disappeared from the map in 18 th century was because Prussians had help from Russia and Austria and Poland at that time was still very weak after surviving the wars with Russia, Sweden, Ottoman Empire and Cossacks. Still, you didn’t manage to get rid of us for good. Don't think that you ever will. :)