Short answers, pulled from the story.
Prince Józef Antoni Poniatowski entered the world on the 7th of May 1763 inside Vienna's Palais Kinsky. His mother Countess Maria Theresia Kinsky von Wchinitz und Tettau belonged to an old and influential Austro-Bohemian aristocratic family.
Poniatowski received the rank of major-general in October 1789 alongside Tadeusz Kościuszko and three others. He became commander of a division in Ukraine and devoted himself to rebuilding the small Polish, Lithuanian Commonwealth's army during deliberations by the Four-Year Sejm that ended with the proclamation of the 3rd of May Constitution in 1791.
French forces blew up the bridge over river White Elster near Leipzig before he could reach it. He tried escape across Elstermühlgraben but badly injured probably shot by allies by mistake drowned in the river.
On the 16th of October during Battle of Leipzig Poniatowski was made Marshal of Empire as reward for services. He had previously led cavalry charges saving his unit from enemy surprise while breakfasting with Murat on the 12th of October.
Remains transported to Poland 1817 buried in cathedral on Kraków Wawel Hill. He lies beside Tadeusz Kościuszko and John III Sobieski.