Duke of Enghien
Czartoryski paid most attention to foreign-affairs for as the tsar's key advisor he exercised practical control of Russian diplomacy. His first act had been to protest energetically against Napoleon's murder of a Bourbon royal prince the Duke of Enghien (20 March 1804) and insist on an immediate rupture with the government of the French Revolution, then under Napoléon Bonaparte, whom the tsar considered a regicide.