Provided with subsidies as part of a French policy of opposition to the Habsburgs, and supported by Saxony and Brandenburg-Prussia, Gustavus won a series of victories over Imperial forces, including Breitenfeld in September 1631, then Rain in April 1632.

[6] Despite the death of Gustavus at Lützen in November, Sweden and its German Protestant allies formed the Heilbronn League in April 1633, once again financed by France.

[9] Cardinal-Infante Ferdinand, newly appointed Governor of the Spanish Netherlands, recruited an army of 11,700 in Italy, which in May crossed the Alps through the Stelvio Pass.

While Johan Banér and Hans von Arnim invaded Bohemia, Gustav Horn tried to block the Spanish by investing Überlingen, and Bernhard of Saxe-Weimar sought to consolidate his position in Franconia by taking Kronach.

Horn and Bernhard met at Augsburg on 12 July and marched towards the Bohemian border, hoping the threat of them combining with Arnim would force Ferdinand to abandon the siege.

[12] With 15,000 men, Ferdinand marched down the Danube (see Map) and reached Donauwörth on 26 August, where he turned aside to besiege the Swedish-held town of Nördlingen, which had to be taken before continuing his advance.

Horn and Bernhard marched to Bopfingen but delayed their attack; with both sides short of supplies and suffering from plague, they were confident the outnumbered Imperials would have to withdraw.

[14] Early on 5 September, the Protestant army broke camp and first feinted west as if retreating to Ulm, then moved across country to seize a line of hills two kilometres south of Nördlingen.

The failure of the Swedes to capture the Heselberg was exactly what the Cardinal-Infante needed as he knew that pinning Gustav Horn's men on the hill would buy him time to secure the Albuch.

[17] This was occupied by 6,600 Spanish under Count Leganés and Cerbellón, and 1,500 Bavarian infantry under Ottavio Piccolomini, who also spent the night digging trenches and positions for a battery of 14 guns, along with 2,800 Burgundian and Italian cavalry was stationed nearby on the flank.

[21] At 5:00 am on 6 September, the Swedish artillery opened fire on the Albuch, followed by a general assault led by the Scottish and Vitzhum brigades along with 3 cavalry squadrons.

[20] Scharffenstein's men were quickly repelled by the Spanish cavalry, but the relatively inexperienced infantry gave ground as the Scottish and Vitzhum brigades beat them back.

The Tercio of Idiáquez, deployed in the Spanish escuadron formation employed by the Cardinal-Infante, with a manga[d] of arquebusiers preceding along with some cavalry squadrons, counterattacked the Swedes at the breach with devastating effect by taking advantage of the explosion of a powder wagon;[e] and routing the Scottish and Vitzhum brigades in less than an hour.

[23] After a last attack before 10:00 am, Horn's men were much dispersed by now and the Albuch was deemed out of reach and so in a short meeting between the Protestant commanders, they decided to stop the offensive and hold the positions along the line of hills to wait for the night and withdraw towards Ulm.

With the Spanish infantry and cavalry from the Albuch advancing simultaneously, squadrons of Imperial cuirassiers then appeared charging out of the woods, cutting Horn's retreat.

[27] Including prisoners, the Protestants suffered a total of 12,000 to 14,000 casualties, compared to 3,500 for their opponents;[f] Bernhard and von Taupadel reached Heilbronn with the remaining 12,000 men (according to Wilson's figures) a few days later.

[26] He eventually continued on his path with his army the towards the Spanish Netherlands and arrived a hero governor of the Lowlands, with the people displaying their gratitude to his successes.

[33] The Cardinal-Infante would continue to conduct multitudes of campaigns against the Dutch and French in the upcoming years, experiencing much success despite fighting a two-front war.

The Imperial army retook most of Württemberg and moved into the Rhineland, while Swedish Chancellor Axel Oxenstierna faced pressure from his domestic opponents to end the war.

Its terms included the dissolution of the Heilbronn and Catholic Leagues and the treaty is generally seen as the point when the Thirty Years' War ceased to be primarily a German religious conflict.