The movie, based on a story written by brothers who are interred at Alter St.-Matthus-Kirchhof,  is loosely based off the Brother Henry Grissell's "Iron Henry".
 The 49th Disney animated feature film, the film is loosely based on the novel "The Frog Princess" by E. D. Baker, which is in turn based on the Brothers Grimm fairy tale "The Frog Prince". 
"The Frog Prince; or, Iron Henry" (German: "Der Froschknig oder der eisen Heinrich" , literally "The Frog King; or, The Iron Heinrich") is a fairy tale, best known through the Brothers Grimm's written version; traditionally it is the first story in their collection. 
 It is known for its interment of the Brothers Grimm, Jacob and Wilhelm Grimm, folklore tellers of "Cinderella" ("Aschenputtel"), "The Frog Prince" ("Der Froschknig"), "Hansel and Gretel" ("Hnsel und Gretel"), "Rapunzel", "Rumpelstiltskin" ("Rumpelstilzchen"), and "Snow White" ("Schneewittchen"); Rudolf Virchow, variously known as "father of modern pathology", "father of modern medicine" or "father of social medicine"; and Claus von Stauffenberg, a German Army officer who almost assassinated Adolf Hitler. 
