The Winter War : Russia's invasion of Finland, 1939-1940 by Robert Edwards

"The Russians meanwhile had markedly damaged their international standing and effectively ruined their military reputation-to such an extent, as this probing chapter in World War II history demonstrates, that Germany, with proud-blooded Finland as an ally, dared to launch its 1940 invasion of Russia. At the same time, though, the fiasco of the Winter War forced Stalin to acknowledge the shortcomings of the Red Army and to reform it: Germany would fall at Stalingrad in 1941." - Editorial Reviews