The Fulda Gap is an area between the Hesse-Thuringian border (the former Inner German border) and Frankfurt am Main that contains two corridors of lowlands through which tanks might have driven in a surprise attack effort by the Soviets and their Warsaw Pact allies to gain crossing(s) of the Rhine River. Named for the town of Fulda, the Fulda Gap was strategically important during the Cold War. The Fulda Gap is roughly the route along which Napoleon chose to withdraw his armies after defeat at the Battle of Leipzig. Napoleon succeeded in defeating a Bavarian-Austrian army under Wrede in the Battle of Hanau not far from Frankfurt; from there he escaped home to France. The route was also used by the U.S. XII Corps during World War II to advance eastward in late March and early April 1945.
During the Cold War, the Fulda Gap was one of two obvious routes for a hypothetical Soviet tank attack on West Germany from Eastern Europe, especially East Germany; the other route was the North German Plain (a third, less likely, route was up through the Danube River valley in Austria). The concept of a major tank battle along the Fulda Gap was a predominant element of North Atlantic Treaty Organisation (NATO) war planning during the Cold War, and weapons such as nuclear tube and missile artillery, the nuclear recoilless gun/tactical launcher Davy Crockett, Special Atomic Demolition Munitions, the AH-64 Apache attack helicopter, and A-10 ground attack aircraft were developed with such an eventuality in mind.