Then, in 1544, five French galleys under Polin, including the superb Réale, accompanied Barbarossa's fleet, on a diplomatic mission to Suleiman. The French fleet accompanied Barbarossa during his attacks on the west coast of Italy on the way to Constantinople, as he laid waste to the cities of Porto Ercole, Giglio, Talamona, Lipari and took about 6,000 captives, but separated in Sicily from Barbarossa's fleet to continue alone to the Ottoman capital. Jerôme Maurand, a priest of Antibes who accompanied Polin and the Ottoman fleet in 1544, wrote a detailed account in Itinéraire d'Antibes à Constantinople. They arrived in Constantinople on 10 August 1544 to meet with Suleiman and give him an account of the campaign. Polin was back to Toulon on 2 October 1544.
Question: When did the French join Barbarossa's fleet?
Answer: his attacks on the west