 Rear Admiral Sir Alexander Cochrane raised the first Corps of Colonial Marines in 1808 while commander @-@ in @-@ chief of British naval forces on the Leeward Islands station during the Napoleonic Wars . The British had captured the island of Marie Galante earlier that year , but the French governor of Guadeloupe attacked the island on hearing that illness had weakened its British garrison . Marie Galante slaves assisted the British when promised that they would not be returned to their proprietors ; by this means , the island was preserved under British control until the arrival of three companies of the 1st West India Regiment . 
