 Complete the following phrase:  During the Civil War, the Union assumed the role of enforcing American trade and extraterritoriality in Japan stemming from the Convention of Kanagawa and subsequent unequal treaties, which at this time the US had the ports of Shimoda, Hakodate, Yokohama, Nagasaki, and Niigata open for US trade. Japan had hoped that the civil war would allow Japan to take back sovereignty of their land if the US was occupied with the civil war. However, the Union sent the USS Wyoming to Japan to protect its interests in the country and fought in the Battle of Shimonoseki Straits during the 