Complex sentence: Florimond Claude, comte de Mercy-Argenteau (1727--1794), Austrian diplomat, son of Antoine, comte de Mercy-Argenteau, entered the diplomatic service of Austria, going to Paris in the train of Reichsfürst Kaunitz.
Split into simpler sentences: Florimond Claude, comte de Mercy-Argenteau (1727--1794) was an Austrian diplomat. He was the son of Antoine, comte de Mercy-Argenteau, and entered the diplomatic service of Austria going to Paris in the train of Reichsfürst Kaunitz.