King Cotton was a slogan used by southerners (1860–61) to support secession from the United States by arguing cotton exports would make an independent Confederacy economically prosperous, and—more important—would force Great Britain and France to support the Confederacy in the Civil War because their industrial economy depended on textiles derived from cotton. The slogan was successful in mobilizing support: by February 1861, the seven states whose economies were based on cotton plantations had all seceded and formed the Confederacy. However, the other eight slave states remained in the Union. To demonstrate their economic power southerners spontaneously refused to sell or ship out their cotton in early 1861; it was not a government decision. By summer 1861, the Union blockade shut down over 95% of exports. Since the Europeans had large stockpiles of cotton, they were not injured by the boycott—the value of their stockpiles went up. To intervene meant war with the U.S. and a cutoff of food supplies, so Britain did not intervene. Consequently, the strategy proved a failure for the Confederacy—King Cotton did not help the new nation.