'Adler' (vi) was a German undertaking designed to re-establish the land link between Generaloberst Ferdinand Schörner’s Heeresgruppe 'Nord' and Generaloberst Georg-Hans Reinhardt’s Heeresgruppe 'Mitte' in the area between Schrunden and Leckava on the Venta (Windau in German) river in Latvia (13 October 1944).