After the signing of the Treaty of Amity and Commerce, The Kingdom of Prussia became therefore one of the first nations to officially recognize the young American Republic after the Revolution. The Treaty was signed to promote free trade and commerce and became a benchmark for subsequent free trade agreements and treaties. In addition, the treaty demanded the unconditionally humane custody for war prisoners, a novelty at the time. The treaty was renewed in 1799 after negotiations with then-United States Ambassador to Prussia John Quincy Adams.[2] While the U.S. did not have a formal mission to Prussia, the construction of the current embassy to Germany began after the appointment of Adams as the ambassador in Berlin which was the capital of Prussia at the time.
On May 1, 1828, both countries signed a Treaty of Commerce and Navigation which revived both the original Treaty of Amity and Commerce and its renewal in 1799.[3] The treaty after German reunification remained intact as the treaty was regarded as binding and its provisions served for adjustments for commercial relations between Germany and the United States. It was until the outbreak of World War I that the treaty came under question and was no longer in continuance.[4]
By the late 1840s through the 1860s, trade between both countries grew rapidly. In 1846, the United States, Prussia, and Bremen, then the main German harbor for the American trade, founded the Ocean Steam Navigation Company (OSNC), directed against British maritime supremacy in the North Atlantic. In part, the company was subsidized by Prussia. In 1855, Prussian Secretary of Trade August von der Heydt remarked about trade with the U.S. describing "the importance of the United States for us as a market for our products has grown by leaps and bounds from one year to the next, and to such a degree, that the customs duty of that nation is, for our own industrial interests, of greater importance than that of most other states."[5]
After the Austro-Prussian War of 1866, the Kingdom of Hanover and Duchy of Nassau, were subsequently merged directly into the Kingdom of Prussia. From this point, Hanover and Nassau had relations with the United States as a part of the Kingdom of Prussia.[6]
Relations ended on February 3, 1917, when U.S. President Woodrow Wilson instructed Secretary of StateRobert Lansing to notify the German Ambassador to the United States that all diplomatic relations between the U.S. and the German Empire were severed. On April 6, 1917, Wilson declared war on Imperial Germany.[10]
^Schmitt, Hans A. (1975). "Prussia's Last Fling: The Annexation of Hanover, Hesse, Frankfurt, and Nassau, June 15 -October 8, 1866". Central European History. 8 (4): 316–347. doi:10.1017/S0008938900018008. S2CID145525529.