The war continued and St Aloüarn was posted to Martinique on the 74-gun "Défenseur". His father and uncle were both killed when the "Juste" was destroyed in 1759, at the Battle of The Cardinals (also known as the Battle of Quiberon Bay). During 1759–62, St Aloüarn served in France on smaller vessels and on shore. Between 1762 and 1767, St Aloüarn served on the 116-gun "Royal Louis" and the frigate "Infidèle", at Martinique and Brest. He was promoted in 1763 to lieutenant. St Aloüarn took command of the storeship "Ecluse" in 1767, followed by the "Aber Wrac'h" in 1770.