One of the Rainbow Plans, War Plan Black was the name of an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 military plan to fight Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 in the early 20th century. The best-known version of Black was conceived as a contingency plan during World War I in case France fell and the Germans attempted to seize French possessions in the Caribbean, or launch an attack on the eastern seaboard. War Plan Black called for the United States to plant mines and have submarines on patrol at sites Germany might seize for a foothold in the Caribbean. It was revised in 1916 to concentrate the main US naval fleet in New England, and from there defend the US from the German navy. Following Germany's defeat in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, Plan Black was no longer as important as it once was.