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 Shimonoseki campaign against the Chōshū Domain, responding to the Imperial order to expel the "barbarians". The Lincoln administration demonstrated to European powers that the Union had the capability to protect its assets in the middle of a civil war, which further strained Japanese relations with the Union. After the war, the decommissioned ironclad CSS "Stonewall" would later be given the Imperial Japanese Navy.