The title was created in 1270 by Louis IX of France, during the Eighth Crusade. At the time it was equivalent to the office of Constable of France. The Admiral was responsible for defending the coasts of Picardy, Normandy, Aunis, and Saintonge. In times of war, it was his responsibility to assemble French merchant ships into a navy. He had to arm, equip, and supply the ships for the course of the war, and give letters of marque to corsairs. In peacetime, he was responsible for the maintenance of the royal fleet (when one existed). He was also responsible for maritime commerce and the merchant fleet.
During the modern era, few admirals were sailors — moreover, with the exception of Claude d'Annebault, none of them actually commanded the fleet. It must be said that the actual power of the admiral was rather small, partly because of the creation of other admirals (the Admiral of the Levant for Provence, the Admiral of Brittany, and the Admiral of the West for Guyenne), and because of the creation of the General of the Galleys and the Secretary of State for the Navy.
The title, like the title of Constable, had much more political importance (which would eventually lead to the suppression of both titles). It was also a lucrative position: the admiral was allocated a part of the fines and confiscations imposed by the admiralty, and he had a right to unclaimed ships and shipwrecks as well as a tenth of the spoils taken in battle. He also had juridical rights, comparable to those exercised by the constable and the marshal. This was known as the Table de marbre, after the seat of the admiralty in Paris. A second headquarters of the admiralty was established at Rouen, and about 50 other headquarters were set up at various other places around the coast of France. These tribunals judged cases dealing with fishing disputes and any crimes committed in the country's ports.
The Admiralty was suppressed in 1627 by Cardinal Richelieu, who had been named to the newly created post of Grand Master of Navigation and who wanted to bring all naval authority under one position. The position was recreated in 1669, but was now only an honorific title. The first new admiral was Louis, Count of Vermandois, who at the time was only 2 years old. Thereafter, only Louis Alexandre, Count of Toulouse involved himself in maritime affairs.