In a number of works from the late 1970s, Kiefer references the Vistula, Poland's longest river, which has figured in numerous territorial disputes between Poland and its neighbors to the east and west-Russia and Germany-over the past two centuries. The works' most obvious inference is perhaps Hitler's invasion of Poland in 1939, when a poorly equipped and vastly outnumbered cavalry rode out to meet the oncoming German tanks. Inscribed across the bottom of one drawing is Weichsel, Weichsel, weiße Weichsel (Vistula, Vistula, white Vistula), lyrics to a song popular during the Third Reich. Another drawing, Ride to the Vistula, shares its title with a 1941 book by the Silesian author Alphons Hayduk, a historian of that region and member of the Nazi party (the book was banned in West Germany after the war). In all of Kiefer's Vistula-themed works, horses represent Poland-its vulnerability and perhaps its valiance.