On the return journey, the force was attacked by a British squadron off Madagascar and defeated, leaving the British in complete control of the Indian Ocean. The Indian Ocean was a vital part of the chain of trade links that connected the British Empire. Merchant ships from China, Arabia and East Africa crossed it regularly and at its centre was the British-held continent of India, from which heavily laden East Indiamen brought millions of pounds worth of trade goods to Britain every year. Trade with India was vital to the financial security of Britain and consequently the trade routes across the Indian Ocean were a high priority for protection from the Royal Navy and at serious risk from French raiders. The outbreak of the Napoleonic Wars in 1803, following the brief Peace of Amiens that had ended the French Revolutionary Wars, placed the Indian Ocean trade routes under threat from Dutch cruisers operating from Cape Town and the Dutch East Indies and French ships based on Isle de France and the newly renamed Île Bonaparte. By 1808, most of the Dutch colonies had been neutralised in a series of brief but successful campaigns; the Cape by Sir Home Riggs Popham in January 1806 and the Dutch island of Java by Sir Edward Pellew in a campaign that ended in December 1807. The French Indian Ocean islands were however far more defensible: heavily fortified, garrisoned by regular French soldiers and several months voyage from the nearest British port, they presented a much greater challenge to the limited British forces available in the region. At the beginning of the war, as in the preceding conflict, French privateers operated from the islands, including a fleet of small vessels run by Robert Surcouf. Supplementing these ships were occasional French naval vessels, principally the frigate "Piémontaise" (captured in March 1808) and the old frigates "Sémillante" and "Canonnière". These ships operated independently of one another and achieved minor successes against smaller British warships and merchant vessels but were not powerful enough to have a serious effect on the Indian Ocean trade routes. In August 1808, "Sémillante" and "Canonnière" were downgraded to armed storeships and sent back to France. To replace these ships, four large frigates under Jacques Hamelin were sent to Governor Charles Decaen on Isle de France in the late autumn of 1808. These vessels, "Vénus", "Manche", "Caroline" and "Bellone" were large and powerful ships under orders to operate from Isle de France and Île Bonaparte against British trade in the Indian Ocean.