In 1806, Willaumez led a French squadron in the Atlantic campaign of 1806, sailing to Brazil and the West Indies and attacking British merchant shipping.

In May 1808, Willaumez attempted to regroup warships scattered in Brest, Lorient and Rochefort into an eighteen-ship squadron to defend the French West Indies; adverse weather and the poor state of the squadron thwarted the plan and he ended up being blockaded in Rochefort, leading to a catastrophic defeat at the Battle of the Basque Roads and falling out of favour with Napoleon.

[3] In 1777, at the age of 14, he enlisted as an apprentice pilot boy on the 74-gun Bien-Aimé, under Captain de Bougainville,[4] in the squadron under Admiral du Chaffault.

[3] Arrived at Lorient, and finding no ship in need for his services, Willaumez went to Brest, where he was quickly enlisted as aid-pilot on the 90-gun Ville de Paris,[5] which in late 1780 was being overhauled.

[6] Weary of his inactivity during the work on Ville de Paris, Willaumez requested a transfer on a departing ship, and was appointed as a pilot to the frigate Amazone, under La Pérouse, in January 1781.

[4][5] Cruising in the Bay of Biscay, Amazone captured the twelve-gun privateer lugger Pitt; Willaumez was given command of a prize crew and sailed her to Lorient.

[8] In this period, Willaumez took upon himself to study navigation and astronomy, for which he displayed such passion that the chief of the station, Saint-Riveuil, offered him a sextant and a chronometer.

[9] In recognition of his conduct, the governor of Mauritius granted Willaumez command of the corvette Légère and tasked him to carry the documents of D'Entrecasteaux' expedition to France.

[11] Régénérée was part of a two-corvette and four-frigate naval division under Rear-Admiral Sercey, tasked to sail to Mauritius and prey on British merchantmen in the Indian Ocean.

[12] The frigates departed the Indian Ocean theatre in September sailing from Mauritius to Rochefort[13][14] and escorting two merchantmen of the Spanish Royal Company of the Philippines to Europe.

[13] En route, the two frigates and two merchantmen stopped at Îles de Los to effect repair and gather water;[15] they anchored at Tamara, Vertu disassembling her masts and yards to restore her rigging, while Régénérée sailed to the nearby island of Factori.

[16] In November 1802, after General de Rochambeau replaced Charles Leclerc, he started executing blacks by drowning; he had the entire garrison of Fort Dauphin transferred to Swiftsure and thrown overboard by her crew.

"[17][18][note 3] After 18 months, Willaumez transferred his flag on the frigate Poursuivante, on which he served successively at the Western and Southern stations, and carried out a number of raids against the Haitian revolutionaries.

[16] On 27 June 1803, Poursuivante departed Les Cayes, bound for Cap-Haïtien,[16] in the company of the sixteen-gun corvette Mignonne,[19] under Jean Pierre Bargeau.

[21] After two hours of mutual cannonade, the ships were close to shore and at eleven, the wind fell, favouring the shallower and more manoeuvrable frigate, which quickly came in position to rake Hercule and delivered a devastating broadside at her stern.

[21] The damage and confusion on Hercule were such that, probably fearing to run aground,[22][23] she effectively dropped out of action,[21] allowing Poursuivante to reach the safety of Môle-Saint-Nicolas.

[28] Its mission was to sail to the Cape of Good Hope, replenish its water and provisions, harass British interests wherever opportune, and return no later than 15 months after.

[28] In the first days of the cruise, the division captured a number of prizes, before making a two-day port call at the Canary Islands to replenish its food.

[29] With food supplies now unavailable and many of his men suffering from scurvy, Willaumez set sail for Brazil, where he arrived in early April 1806.

[29] There, he divided his squadron into three divisions, which he dispersed from Cayenne to the 9th parallel south; however, this tactic yielded disappointing results, and Willaumez regrouped his ships.

[30] Three days later, on 6 July, off Saint Thomas, Willaumez spotted a British squadron comprising five ships of the line and seven frigates and corvettes, which sailed away with the advantage of the wind.

[32] Willaumez fruitlessly searched the missing ship in several directions until he became certain that she was en route for France, and returned to his station; the convoy, however, had already passed.

[32] After a four-month stay in Havana, Willaumez departed for Chesapeake Bay to rejoin Patriote, Éole and Valeureuse, which had taken refuge there after the hurricane.

[32] The division had returned dispersed and lost several ships: Impétueux had managed to build a jury rudder, but had been intercepted by a British squadron and forced to beach herself to avoid capture; Éole and Valeureuse had been sold for scrap in Annapolis; Vétéran had found an unlikely shelter in Concarneau, normally far too shallow to harbour a ship of the line, where she was blockaded; Patriote later reached Brest, and Cassard, Lorient.

[34] It departed on 21 February 1809, with orders to make its junction with the division of Lorient that was blockaded in its harbour, attach these ships, attack the British squadron blockading Rochefort, attach the Rochefort squadron under Admiral Bergeret[35] and, by then totaling 18 ships, sail to the Caribbean to rescue Martinique and Guadeloupe.

[10] During the Empire, Willaumez advocated the construction of strong, sixty-gun frigates, capable of carrying food for ten months and water for four, mounting the new 30-pounder long gun rather than the 36- and 24-pounders that dated from before the French Revolution.