Battle of Nördlingen ( 1634 ) The Battle of Nördlingen ( ; ; ) was fought on 27 August ( Julian calendar ) or 6 September ( Gregorian calendar ) , 1634 during the Thirty Years ' War . The Roman Catholic Imperial army , bolstered by 18 , 000 Spanish and Italian soldiers , won a crushing victory over the combined Protestant armies of Sweden and their German - Protestant allies ( Heilbronn Alliance ) . After the failure of the tercio system in the first Battle of Breitenfeld in 1631 , the professional Spanish troops deployed at Nördlingen proved the tercio system could still contend with the deployment improvements devised by Maurice of Orange and the late Gustavus Adolphus of Sweden . Prelude . After the Protestant victory in the Battle of Lützen two years before , the Swedes failed to follow up their victory due to the death of their king , Gustavus Adolphus . As a result , the Imperial forces had begun to regain the initiative . In 1634 a Protestant Saxon and Swedish army had invaded Bohemia threatening the Habsburg core territories . The future Holy Roman Emperor , Ferdinand of Hungary , decided to attack the Protestant territories in Southern Germany to draw the main Swedish and German armies away from Bohemia . Both sides were aware that Spanish reinforcements under his cousin , the Cardinal - Infante Ferdinand , were en route from their dominions in Northern Italy . The Spanish army had marched through the Stelvio Pass trying to open a new " Spanish Road " , and take their Commander to his Governorship of the Spanish Low Countries . The Protestant commanders decided they could not ignore the threat and combined their two largest armies near Augsburg on July the 12th , the Swabian - Alsatian Army under Gustav Horn and the so - called Franconian Army under Bernhard of Saxe - Weimar . Both armies were named after their main operation area and belonged to the Heilbronn Alliance ( Sweden ' s German - Protestant allies under the directorate of the Swedish chancellor Axel Oxenstierna ) . They were mainly consisting of German ( " the Blue brigade " ) and some Scottish allies ( " the Green brigade " ) with a few national Swedish / Finnish regiments ( mostly cavalry ) and one national Swedish infantry brigade ( " the Yellow brigade " ) . The Protestants proved unable to prevent the fall of Regensburg to Ferdinand of Hungary and desperately pursued him westwards in an effort to prevent the merger of the two Habsburg armies . On 16 August the Cardinal - Infante crossed the Danube at Donauwörth . Despite their best efforts the Protestant armies were still behind when Ferdinand and the Imperials set down to besiege the town of Nordlingen , in Swabia and await the Cardinal - Infante who arrived before the city on the 2nd September - three days before the Protestants . Battle . The cousins , Ferdinand and Ferdinand , prepared for battle , ignoring the advice of the more experienced generals , such as the Imperial general Matthias Gallas . Most of the generals felt a full engagement against two of the most experienced Protestant commanders was reckless and unlikely to have a positive outcome . However the cousins were supported by the Count of Leganés , the Spanish deputy commander . He appreciated that the Catholic army was significantly superior in numbers and had at its core the highly trained professional Spanish Infantry who had not been present at previous Swedish victories over the Imperials . Bernhard and Horn also prepared for battle , although this may not have been a mutual decision . Bernhard felt that whatever the odds an attempt must be made to relieve Nordlingen . Horn seems to have been reluctant to do so given the ragged state of the Protestant armies . Both commanders seem to have underestimated the numerically superior enemy forces . This may have been due to incorrect reports , or disbelieving those they had received . Whatever the reason Horn and Bernhard estimated that the Spanish reinforcements numbered only 7 , 000 and not 21 , 000 ; in addition to the 12 , 000 Imperials , this gave the Habsburgs a considerable superiority over the 26 , 000 Protestants . During the battle , almost anything that could go wrong went wrong for the Protestant forces . This was due to the strong defensive efforts of the Spanish infantry , the feared " Tercios Viejos " ( Old Tercio s ) , mainly those commanded by Fuenclara , Idiáquez , and Toralto . Fifteen Swedish assaults by Horn ' s right wing , consisting of the brigades Vitzthum , Pfuel and one of the Scots Brigades ( Colonel William Gunn ) , supported by the brigade of Count Thurn ( Black and Yellow Regiment ) on the hill of Albuch , were repulsed by the Spaniards with the decisive support of Ottavio Piccolomini ' s Italian cavalry squadrons , under direct orders of another Italian commander , the loyal servant to the Spanish Crown , Gerardo di Gambacorta di Linata . On the left of the Protestant line the left Swedish wing under Bernhard of Weimar and the Imperial - Bavarian troops had avoided closing with each other , until late in the battle . The Imperial commanders observed the weakened condition of Bernhard ' s troops , who had been sending large numbers of reinforcements to assist the Swedish troops . They ordered an advance by the Imperial troops which resulted in the quick collapse and rout of the weakened Swedish left wing infantry brigades . Pursuit of Bernhard ' s troops threatened to cut off any escape route of the Swedish units , who also promptly broke , turning into a panic stricken mob and leaving their side of the field to the Spanish troops of the Cardinal - Infante Ferdinand . Gustav Horn af Björneborg was captured , his army was destroyed , and the remainder of the Protestants who successfully fled to Heilbronn were only a remnant of those engaged . Aftermath . The battle was one of the most crushing defeats the Protestants sustained during the war . With its army substantially reduced , Sweden would lose its predominant role in the German area . Meanwhile , the victory led most of the Protestant princes of the Empire to seek a separate peace with the Emperor , which was achieved by the Treaty of Prague in 1635 . With Imperial forces threatening to totally dominate the Empire and with Spanish troops firmly settled on the western bank of the Rhine , great Habsburg armies had almost completely surrounded France ' s frontiers . Richelieu decided France needed to go beyond merely financing the enemies of the Habsburgs ; entering the war mainly against Spain and thus opening a second front in the Catholic Low Countries . In the long term , the battle proved to be just another twist in the complicated war . It ensured that a triumph of the Swedish led Protestants powers , would not occur . This enabled the Counter - Reformation to preserve its gains against the Reformation in central Europe . That said , the victory did not lead to an overall Catholic - Habsburg victory , as the Spanish and Imperialist forces would suffer serious setbacks later in the war . The Swedish army would recover by defeating a combined Imperial and Saxon army at the battle of Wittstock only two years after Nördlingen . Then the Swedish army would inflict several more defeats on the Imperialists . Eventually , the Swedish army besieged Prague and reached the gates of Vienna . Ultimately , the defeat of the Swedish forces at Nordlingen was responsible for French goals taking precedence at the negotiations for the Treaty of Westphalia with a significant effect on the political map of the Empire .