The effect of these changes was profound. Gustav had been largely ignored by most of Europe after his mixed results in Poland, and when he arrived in Germany in 1630 he was not immediately challenged. He managed to build up a force of 24,000 regulars and was joined by a force of 18,000 Saxons of questionable quality under von Arnim. 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. With one flank now open Tilly nevertheless had a major positional advantage, but Gustav's smaller and lighter units were able to easily re-align to face the formerly open flank, their light guns cutting into their ranks while the heavier guns on both sides continued to exchange fire elsewhere. Tilly was soon driven from the field, his forces in disarray.