 Complete the following phrase:  After the immediate defense of Dresden, though, Napoleons situation deteriorated. Vandamme pursued the retreating Army of Bohemia, expecting to be supported by St. Cyr and General Marmont, who were still busy in Dresden. Vandamme approached the Russian corps commanded by Ostermann-Tolstoy, but left a valley behind him unprotected as he descended out of the mountain into Bohemia. As he engaged Ostermann-Tolstoy, he saw some troops behind him, which soon attacked him; thus beset from two sides, his young troops were unable to defend themselves; at the 