The Battle of Breitenfeld was the first major Protestant victory in the Thirty Years' War.

Prelude

In late August 1631, the Imperial Commander Johann Tserclaes, Graf von Tilly invaded Saxony in hopes of forcing the ruler of the Electorate of Saxony, John George I to abandon an alliance he planned to conclude with Gustavus Adolphus, King of Sweden. Gustavus Adolphus responded by uniting his army with the elector's forces, hoping to fight Tilly and force him to leave Saxony. Tilly arrayed his forces north of Leipzig at Breitenfeld and prepared to meet Gustavus Adolphus.

Tactics

The real difference between the two armies was tactics.

The Imperial forces arranged their army in squares, called tercios (Spanish). This was the traditional formation for the period, with each square having a fifty man front and a depth of thirty men. The centre comprised pikemen with supporting units of arquebusiers on each flank.

The Imperial army was comprised of seventeen such formations, arranged in three large blocks with the center block placed slightly ahead of the other two. The cavalry was drawn up on each flank, Pappenheim commanding the left and Fürstenburg the right. The left flank was close by Breitenfeld; the right, by Seehausen. Tilly had no reserves except for some cavalry placed behind his infantry.

Gustavus Adolphus, however, arranged his forces in two long lines. Each line was five men deep for pikemen, and six men deep for musketeers. The use of linear tactics enabled Gustavus to create a front that matched Tilly's, while still giving him troops to keep in reserve. Gustavus mixed his artillery, and some cavalry, into the main formation.

The Elector of Saxony arranged his forces in the traditional formation, and all commanders placed most of their cavalry on their flanks. Since the Swedish and Saxon forces deployed separately, this placed cavalry in their center as well as on their flanks.

Battle

The battle began around noon with a two hour exchange of artillery fire. This exchange was ended when Count Pappenheim led a charge of the cavalry on Tilly's left. These cuirassiers advanced seven times, but each time was turned back by the Swedes. The Swedes used the tactic of mixing men armed with muskets with their cavalry, who were able to defeat the light cavalry pistol tactics used by the Imperial forces. Swedish reserve cavalry was also able to extend the Swedish line and countercharge with sabers against the Imperial cavalry. Following the defeat of his seventh assault, Pappenheim and his cavalry quit the field. Pappenheim's heavy cavalry, called the Black Cuirassiers, retreated to Halle.

During this time, Tilly's infantry remained stationary, but the cavalry on his right charged the Saxon cavalry and routed it towards Eilenburg. Seeing an opportunity, Tilly sent the majority of his infantry against the remaining Saxon forces and they fled the field, stopping only briefly to loot the Swedish camp.

Tilly thus defeated forty percent of his enemy and was poised to deliver a devastating flank attack on the remaining Protestants. As Tilly was ordering his infantry to roll up the Swedish line, however, Gustavus Adolphus was able to reorder his second line into an array at a right angle to the front. This deprived Tilly of the opportunity for an attack on the Protestant flank.

Following this, a charge by the Swedish cavalry was able to drive off the rest of the Imperial cavalry. With this help, the Protestant infantry was able to gain the upper hand. Soon under fire from both the excellent Swedish guns and captured Imperial guns, the Imperial infantry was forced to retire from the field.

Aftermath

The Battle of Breitenfeld served as major endorsement of the linear tactics of Gustavus Adolphus. He was able to inflict more than sixty percent casualties on his opponent, and made up his own losses in recruited prisoners. It also had the political effect of convincing Protestant states to join his cause.