A member of the consular guard from 1800, Jérôme was transferred to the navy soon after he was wounded in a duel. He cruised in the West Indies, where he left his ship and went to the United States; there he married (Dec. 24, 1803) Elizabeth (or Elisa) Patterson, whom he brought to Europe in 1805. Napoleon ordered Elizabeth excluded from his states, but Jérôme remained, taking command of a small squadron in the Mediterranean. He then took part in the campaign of 1806. An imperial decree annulled the Patterson marriage. The Emperor then married Jérôme to Princess Catherine of Württemberg and made him king of Westphalia. In the Russian campaign of 1812 Jérôme failed in his assigned mission and was returned to Kassel, Ger.

In 1813, on the fall of the Napoleonic regime in Germany, Jérôme returned to France. He commanded a division on the French left wing at Waterloo and attacked with great pertinacity. On Napoleon's second abdication Jérôme left France, not returning until 1847 when, after the rise of his nephew Louis-Napoléon, he became, successively, governor of the Invalides, marshal of France, and president of the Senate.