1. Blockade by the Allied Forces: The Allied Powers, including Britain and France, imposed a naval blockade on Germany to restrict its access to vital supplies and resources. The blockade made it difficult for German ships to reach American ports, disrupting trade between the two countries.
2. American Neutrality: At the beginning of the war, the United States declared its neutrality and attempted to maintain trade relations with both the Allied Powers and Germany. However, as the war intensified and German submarine warfare threatened American ships and citizens, the United States became increasingly sympathetic to the Allied cause. This shift in public opinion made it more challenging for the US to continue trade with Germany.
3. Lusitania Sinking: In May 1915, the German U-boat U-20 torpedoed and sank the British passenger ship RMS Lusitania off the coast of Ireland. Over 1,100 people, including 128 Americans, lost their lives in the disaster. The sinking of the Lusitania caused outrage in the United States and significantly strained relations between the two countries, leading to further trade restrictions.
4. Zimmermann Telegram: In early 1917, the British intercepted and decrypted a telegram sent by German Foreign Secretary Arthur Zimmermann to the German ambassador in Mexico. The telegram proposed an alliance between Germany and Mexico against the United States, offering Mexico support in regaining its lost territories in Texas, New Mexico, and Arizona. The disclosure of this telegram infuriated the American public and further deteriorated relations with Germany.
5. Entry of the US into World War I: In April 1917, the United States officially declared war on Germany, formally ending any remaining trade between the two countries. The US joined the Allied Powers and contributed troops, supplies, and financial support to the war effort against Germany and its allies.
As a result of these factors, trade between Germany and the United States was effectively brought to a halt during the war years. Trade relations were only restored after the war's conclusion in 1918.