After Swedish plundering in Brandenburg (1631) endangered the system of retrieving war contributions from occupied territories, "marauding and plundering" by Swedish soldiers was prohibited. Meanwhile, a Catholic army under Johann Tserclaes, Count of Tilly was laying waste to Saxony. Gustavus Adolphus met Tilly's army and won a decisive victory at the First Battle of Breitenfeld in September 1631. He then marched across Germany, establishing his winter quarters near the Rhine, making plans for the invasion of the rest of the Holy Roman Empire.