'Festung' was the German codeword for Generalfeldmarschall Wilhelm Ritter von Leeb’s Heeresgruppe 'Nord' to start the creation of a major defensive position on the Eastern Front behind the Volkhov river using Generaloberst Ernst Busch’s 16^th Army and Generaloberst Georg von Küchler’s 18^th Army (16 December 1941 onward).