Complex sentence: Rupert was born in Prague in 1619, during the Thirty Years' War, to Frederick V, Elector Palatine, and Elizabeth Stuart, and was declared a prince by the principality of Lusatia.
Split into simpler sentences: Rupert was born in Prague in 1619, during the Thirty Years' War, to Frederick V and Elizabeth Stuart. He was declared a prince by the principality of Lusatia.