Breton-born French explorer and naval officer Yves-Joseph de Kerguelen-Trémarec (1734 – 1797) had been an unsuccessful privateer during the Seven Years' War and published a chart of the Atlantic waters around Rockall (1771) before being given the command of the third French expedition sent in search of Terra Australis Incognita.
The expedition's two vessels (Fortune and Gros Ventre, reached the small sub-Antarctic Kerguelen Islands in the southern Indian Ocean, claimed them for France.
Kerguelen then returned to Mauritius, while Louis François Alléno de Saint-Allouarn in the Gros Ventre, separated from the Fortune sailed east to the Australian coast at Cape Leeuwin. Saint-Allouarn coasted to Shark Bay, claimed possession of Western Australia for France, buried a proclamation to that effect on Dirk Hartog Island, continued north to around Melville Island before returning to Mauritius via Portuguese Timor and Batavia.
Kerguelen-Trémarec's report to Louis XV grossly overestimated the value of the discovery but resulted in a commission to lead a second, equally unsuccessful expedition to seek Terra Australis in the Rolland and Oiseau.
On his return to France, Kerguelen-Trémarec was imprisoned, but his fortunes changed during the French Revolution. As a perceived victim of France's Ancien Régime, he was released from jail and restored to his position. He was a Vice Admiral aboard the 74-gun third rate Redoutable at the Battle of Groix (1795) but managed to avoid close engagement in the fighting He was the commander of the port of Brest when he died in 1797.
The islands he discovered still bear his name proved desolate and useless and were undoubtedly not Terra Australis. James Cook visited them on his second voyage, but they were not surveyed until the Ross expedition in 1840.