Although the Thirty Years War had been raging for 13 years by the 1st Battle of Breitenfeld, this would mark the arrival of Sweden in the war by becoming the first great Protestant victory. King Gustav II Adolph of Sweden, popularly known to history as Gustavus Adolphus, had landed his army in Pomerania, on the north German coast, in the summer of the previous year. At first both sides waited - Gustav for the support of Brandenburg and Saxony, and Tilly for reinforcements to march from Italy to Frankfurt-am-Oder.

Johann Tserclaes, Graf von Tilly, was the commander of the Catholic League (organised by Duke Maximilian I of Bavaria) who, having won the Battle of Weisserberg (1620) and most of the subsequent encounters, secured the Palatinate for the Catholics in 1624. Meanwhile, von Wallenstein, the Duke of Friedland, had been in command of Emperor Ferdinand II's army, which, together with the League, had driven the Danish from Germany between 1626 and 1629 (when the Edict of Restitution was issued). But when Cardinal Richelieu persuaded the Swedish to join the anti-Imperial cause, general discontent with Wallenstein led to Tilly being given control of the entire Catholic force.

Gustav struck the first blows of the campaign, moving into Mecklenberg and taking the fortresses of Demmin, Greifwalde and Kolberg in March 1631. When the German Protestant princes made overtures of peace, the Emperor refused to even consider altering the Edict, and Tilly, fearing that Gustavus would make for the Elbe, turned west, united his force with Pappenheim's, and laid seige to Magdeberg. Gustav, his movement hindered by uncertainty surrounding his German allies, couldn't save the city, and it was raised to the ground on May 20th 1631, along with 20,000 souls. In reponse, the Protestants now pulled together, whilst Tilly hesitated before then finding success to the west, and finally turning east once again as a reaction to the Swedes threat from Mecklenberg. On August 30th 1631, Johann-Georg, Elector of Saxony, finally decided against his Emperor and promised to support Gustav on the field.

On 15th September 1631, Tilly led the Catholic-Imperial army into Leipzig. Two days later Pappenheim asked him to support his sortie to the north of the city, and so Tilly's army took up position in the suburb of Breitenfeld, ready to give Gustavus Adolphus his first great test. The combined Protestant army outnumbered the Catholic one by 40,000 to 32,000, but the performance of the Saxons - one quarter of Gustav's army - would belie this numerical advantage. Following an Imperial artillery bombardment, Tilly's right wing cavalry under Furstenberg charged against the Saxons to the left of the Swedish line. They quickly broke and fled the field.

But at this moment in history the Spanish tactics of the massed infantry column would not decide the day, because the flexible linear tactics of the Swedish took effect. Gustav Horn, commanding the Swedish left, had been exposed by the flight of the Saxons. In order to prevent an outflanking manouevre, Horn therefore redeployed his own line to form a new flank, and the Imperial attackers began to break.

Meanwhile, on the other side of the battlefield, the musketeers in amongst the Swedish cavalry of Johan Baner fended off attack after attack from Pappenheim's cavalry. The imperial wings in disarray, Horn now moved the Swedish centre against the sixteen large infantry formations in Tilly's centre, whilst a cavalry raid managed to overrun all the Imperial artillery and turn it against them. Unprotected on the flanks, Tilly's line compressed in the foggy confusion, and the battle was decided. Gustav sent his cavalry to pursue the retreating enemy, but by 7pm, and after five hours of fighting, it was all over.

The Protestants suffered 4,500 casualities - two thirds of whom were Saxons - whilst Tilly's army was virtually destroyed. The Imperials suffered 14,000 battle casualties (half of them prisoners) and, as several thousand stragglers felt the wrath of vengeful Saxon peasants, the casualty rate reached an incredible 70%. Tilly was forced to withdraw west, across the Weser, and Gustav was master of Bohemia.

Unfortunately there is little to see of the battlefield today because the Leipzig ringroad has been built right through the middle of it, almost along the Imperial line, so that the middle of Tilly's position is actually now marked by a large interchange. But the part of the battlefield nearest Breitenfeld itself - i.e. the positions of Pappenheim and Baner - is still worthy of note.