The cotton gin transformed cotton into a powerful tool of American foreign policy.

In 1793, Eli Whitney patented the cotton gin, a device that mechanized the removal of seeds from short-staple cotton. Before this invention, a single person could clean only about one pound of cotton per day. The machine increased this output to 50 pounds daily, causing U.S. cotton production to skyrocket from 1.5 million pounds in 1790 to 167 million pounds by 1820.By the mid-19th century, the American South provided 77% of the cotton used in British textile mills. This economic dominance led Senator James Henry Hammond to declare in 1858 that 'Cotton is King.' Southern politicians believed that if they withheld exports, the British economy would collapse, forcing the United Kingdom to intervene in the American Civil War on behalf of the Confederacy.However, the 'King Cotton' diplomacy failed due to a massive surplus in European warehouses in 1860 and the subsequent development of new plantations in Egypt, Brazil, and India. The British government also prioritized avoiding war with the Union, which provided essential grain imports. This overestimation of economic leverage ultimately left the Confederacy without the foreign recognition or military support it desperately needed.