German soldiers of Army Group South (Heeresgruppe Süd) with their Kubelwagen on a muddy eastern front road.
The Rasputitsa seasons in Russia are a great defensive advantage in wartime. The month-long muddy season (season without roads) occurs twice annually; Spring when the ice and snow melts, then during the Autumn rains. The quagmire slowed the Germans during their 1941 advance on Moscow. It staggered mobile units, as wheeled transports and supply vehicles sunk in the mud. An issue they encountered was the inability to keep Panzer units outfitted and fueled as they advanced further than their supplies could.