Besides the blockade, the US Navy was showing the flag around the world. The US also maintained its embassies and other diplomatic missions in various places. But this week I learned that the US Navy while fighting a civil war, almost got into a shooting war with Japan in 1863-64.
Apparently the Emperor at the time was heading toward Meiji restoration by taking direct power back from the shoguns who had run Japan for hundreds of years. But he was none too fond of foreigners. Trade between Japan and "Westerners" was just opening up. Then the Emperor issues his expel all foreigners order. It went downhill from there.
British, American and French merchant ships were fired on in the Straits of Shimonoseki Straits which separates Honshu and Kyushu. The USS Wyoming was in Yokohama when the US flagged ship the Pembroke was fired on. The Wyoming did not take that lying down. They sailed into the Straits and let the Japanese know they didn't take too kindly to their countrymen being shot at. The Japanese local fleet shot back. The end result was the local fleet sunk and the Wyoming severely damaged.
I found out about this incident while reading the Official Records of the Navy in the Civil War. Then I found the deck log of the Wyoming during that time period is available online through the National Archives. I may incorporate some of the Wyoming's activities in Japan into my research. Because its all happening everywhere all at once.