The First Battle of Polotsk began on 16 August, with Marshal Nicolas Oudinot commanding the II and VI Corps against Peter Wittgenstein's Russian I Corps. On the first day, the 30,000 Russians defeated the 24,000 Allies and Oudinot was wounded. Saint-Cyr took command and withdrew most of his troops to the south bank of the Daugava River on 17 August. He then built a concealed bridge and secretly shifted his small army to the north bank on the night of 17–18 August. At 3:00 PM, Saint-Cyr attacked the surprised Russians with the Bavarian VI Corps on the right, the French II Corps in the center, and the French cavalry on the left. Covered by a bombardment from 30 cannons, Deroy's 19th Division stormed the village of Spas while Wrede's 20th Division attacked farther to the right.