Prince Honore IV was born on May 17, 1758 to Prince Honore III and Princess Maria-Caterina de Brignole-Sale. He suffered probably more than any other of his family from the consequences of the French Revolution. He had the misfortune to be in Paris when the Reign of Terror erupted and he was quickly arrested and thrown into prison. His ex-wife, the Duchess Mazarin, was also arrested by with the help of their family doctor managed to escape with their son Prince Florestan and successfully save themselves. For 15 months he wasted away in confinement, growing weaker and in poorer health. On March 21, 1795 his father died and he became Prince Honore IV of Monaco though at the time the monarchy had been abolished and Monaco annexed to the French Republic as Fort Hercules. Even after his release from prison it took seven years of negotiating before the French regime restored some fraction of their income to Honore IV and his brother Prince Joseph.
However, the future looked brighter for the Grimaldis when the radical elements of the revolution were succeeded by the Consulate and finally the first French Empire of Napoleon Bonaparte. Prince Joseph was to go on to a relatively high placed and distinguished career in the French Imperial forces and Honore IV could have likely enjoyed similar treatment. Unfortunately, his long confinement had left him so sick and frail that he had to restrict himself to the least amount of activity possible. His son, Prince Honore-Gabriel (born in 1778), was able to join his uncle in the imperial service joining a cavalry regiment at the age of 20 and rising through the ranks to become an officer on the staff of Marshal Grouchy and went on to win many laurels in the French Imperial Army.
When the Napoleonic Wars finally ended Monaco was restored by the Congress of Vienna thanks to Prince Talleyrand. However, as Honore IV was still too ill to assume the government of his principality he appointed his brother Prince Joseph as regent on his behalf. Troubles arose though when Joseph stayed in Paris and left Monaco to be administered by a governor. Prince Honore-Gabriel also protested at his uncle being given the position rather than himself. To avoid further trouble Prince Joseph resigned the post and Honore IV appointed Honore-Gabriel regent. He ruled Monaco for the rest of his life while the nominal Sovereign Prince Honore IV remained in Paris where he died on February 16, 1819.