'Keller' was a German undertaking by four patrols of the 6^th SS Gebirgsaufklärungsabteilung (mot.) of SS-Brigadeführer und Generalmajor der Waffen-SS Matthias Kleinheisterkamp’s SS Gebirgsdivision 'Nord' to aid the disengagement of a Finnish long-range reconnaissance detachment along the Yeleyi river near Aschtachma lake (7/10 October 1942).