Armand de Vignero, 3rd Duke of Richelieu was a peculiar personality with a strongly developed sense of honor, due to his descent from the eponymous cardinal-prime minister and the fact that he was sponsored by the king himself Ludovikos ID.
Richelieu had already been imprisoned once for dueling, but he didn't learn from it. In 1734, France and Austria (Hapsburg Empire) were fighting again on the occasion of the succession to the Polish throne. French troops were besieging the city of Philipsburg on the Rhine.
The French had dug siege trenches around the city and Richelieu was in the front line. The cousin of the wife of the Prince de Lixin and the young Prince de Conti served in the same army. The latter in the middle of the battle decided to celebrate his birthday and invited all his noble fellow warriors.
Richelieu accepted the invitation but went to the feast in his dusty uniform, as it was from the trenches. When the other nobles saw him they started to smile. de Lixin said:"Despite his marriage, he carries a lot of dirt on him"...
Richelieu did not let such an insult pass by and immediately challenged him to a duel. The two gladiators with their attendants and other strangers went to a location where they could be seen by the enemies. There their servants lit torches and the duel began.
However the Germans from the besieged city saw the torches and started firing at the gladiators and their escorts believing that an attack was being prepared! A cannonball soon felled an unlucky servant, but the gladiators were undaunted. The duel did not stop even when de Lixin wounded Richelieu.
The latter, stubborn as he was, continued and finally plunged his sword into his opponent's heart with the German shells flying around them... The others present, loudly thanking God that they were still alive, carried Richelieu to the hospital and de Lixin to the grave...
It is worth noting that duels were forbidden in the French army as they tended to become a scourge. This was also the reason why the two gladiators decided to duel in a place where no one could suspect that they could duel, under enemy fire, that is.
The worthy Duke of Richelieu.