Imperial forces regained control of Bohemia in 1646, but inconclusive campaigns in the Rhineland and Saxony made it clear neither side had the strength to impose a military solution.

The Thirty Years' War began in 1618 when the Protestant-dominated Bohemian Estates offered the Crown to fellow Protestant Frederick V of the Palatinate, rather than conservative Catholic Emperor Ferdinand II.

[2] Frederick's replacement by Maximilian as ruler and Prince-elector of the Palatinate changed the nature of the war, drawing in Protestant German states like Saxony and Brandenburg-Prussia, as well as external powers like Denmark-Norway.

[3] Swedish intervention continued despite the death of Gustavus at Lützen in November 1632, but their objectives conflicted with both Imperial states like Saxony, and their regional rivals, such as Denmark.

[4] Emperor Ferdinand III, who succeeded his father in 1637, initiated peace talks in 1643, then delayed negotiations, hoping his position would improve after a planned 1644 military offensive.

[8] Hatzfeldt selected a strong position; the hills and woods negated the superior Swedish artillery, his centre was protected by a stream, the right by a steep slope and deep forest.

In a conference the night before, Torstensson and his senior officers recognised the drawbacks, but agreed to an assault; their co-ordinated attack contrasted with command failures among the Imperial generals.

On his return, he discovered Götzen had misinterpreted his orders, and moved his entire force towards the hill; it became stuck in the woods and broken ground, giving the Swedes time to install artillery and infantry at the crest.

[11] Hatzfeldt moved troops from the centre to cover the retreat of Götzen's men, but unlike the lighter Swedish guns, their artillery got stuck in the mud, and was captured by Arvid Wittenberg.

Although it could not match the Swedish veterans, 25 years of constant war had devastated the countryside, forcing all sides to spend more time foraging than fighting, and drastically reducing their ability to sustain campaigns.

He was joined there by thousands of poorly equipped Transylvanian levies, whose presence simply worsened the supply issues, the besiegers ultimately losing over 8,000 men from disease, hunger, and desertion.

[16] The end of the Danish war in favour of Sweden encouraged Torstensson to make one last attempt on Vienna, but by October, fewer than 10,000 Swedes faced 20,000 Imperialists.