Prussia–United States relations

The Kingdom of Prussia and the United States began diplomatic relations in 1785 following the signing of the Treaty of Amity and Commerce, but formal relations were not established until 1797. Prussia was largely neutral following the onset of the American Civil War in 1861. Likewise, the U.S. acknowledged but was largely uninterested in the 1871 Franco-Prussian War and resulting declaration of the German Empire. Relations would come to an end during World War I when the U.S. declared war on Germany in response to the German Empire’s policy of unrestricted submarine warfare and U.S. support of the Allied Powers.