 Battle was first joined in major form when Johann Tserclaes, Count of Tilly turned his undefeated 31,000 man veteran army to do battle, meeting Gustav at the Battle of Breitenfeld in 1631.Battle opened in traditional fashion, with Tilly's cavalry moving forward to attack the flanks.This drove off the Saxons on the one flank, but on the other Gustav's new combined cavalry/musket force drove off any attempt to charge.