There is a constant chatter in regards to the big Dniper River hydo dam and who may blow it up. In 1941 - the Soviets blew it up and killed over 100,000 Red Army and civilians in the 30 plus foot tidal wave that exploded out. It was claimed the Germans did it - and the Soviets even tried to pin the blame to the Germans at Nuremberg. For decades it was claimed the act stopped the Germans advance. But not all history was re-written to reflect the Soviet view. Its effect was in weeks - not months. Here is the story of the German crossing in August 1941 of the Dniper River - from War Department sources. Excellent details of how to do a large river crossing!