 Complete the following phrase:  During the Mongol invasion of Russia the southern parts of Novgorod land were devastated; Volok Lamsky, Vologda, Bezhetsk, Torzhok were all captured by the invaders. Several versions have been proposed by historians to explain the Mongols refusal to march on Novgorod after the capture of Torzhok on March 5: the upcoming spring thaw, lack of fodder and high losses in the struggle against the Ryazan and Vladimir principalities. On July 15, 1240, Alexander Yaroslavich 