Sea otters and fur seals were severely depleted on the California coast and islands by the 1820s. Hudson's Bay Company entered the coast trade in the 1820s with the intention of driving the Americans away. This was accomplished by about 1840 just as the fur trade industry started dying due to lack of supply and a style change in felt hats—felt was made from fur and the main fur market. In its late period the maritime fur trade was largely conducted by the British Hudson's Bay Company and the Russian-American Company. The depleted supply of sea otters and the easy trade with the British in Fort Vancouver for food stuffs led the Russians to abandon Fort Ross in 1841 and sell the cannon and other supplies to John Sutter who was building up Sutter's Fort near Sacramento, California. The Hudson Bay Company departed from their trading post they had set up in Yerba Buena (San Francisco) in 1845 because of the declining fur trade and the death of their agent there.