1. American commercial interests were pressuring the US government to open Japanese markets for their rapidly expanding industrial output. 2. The American whaling fleet needed access to Japanese ports in order to take on vital supplies, especially coal. 3. In 1849, the USA sent a warship, USS Preble, to Japan to rescue American sailors who had been shipwrecked off the Japanese coast. The Japanese were reluctant to let the Preble into port, but after the threat of force it successfully retrieved the sailors. The USA was angered by the fact that it was clear the sailors had been harshly treated by the Japanese.