Augustus was not done yet. In early 1706 he approached Warsaw with a cavalry force and ordered Johann Matthias von der Schulenburg to move the army assembled in Saxony into Poland–Lithuania. Schulenburg was intercepted and defeated by Carl Gustav Rehnskiöld in the Battle of Fraustadt (Wschowa) on 13 February 1706. The army assembled in Polotsk had been moved to Grodno where it was tactically defeated and forced to withdraw eastwards around the same time. Charles XII then occupied Saxony, forcing Augustus to abandon both the Polish crown and his allies in the Treaty of Altranstädt on 13 October 1706 in which Augustus was forced to give up his claims to the Polish crown.