Battle of White Mountain The Battle of White Mountain ( Czech : " Bitva na Bílé hoře " ) , was an early battle in the Thirty Years ' War fought on 8 November 1620 , in which an army of 30 , 000 Bohemians and mercenaries under Christian of Anhalt were defeated by 27 , 000 men of the combined armies of Ferdinand II , Holy Roman Emperor under Charles Bonaventure de Longueval , Count of Bucquoy and the German Catholic League under Johann Tserclaes , Count of Tilly at Bílá Hora ( " White Mountain " ) , near Prague ( now part of the city ) . The battle marked the end of the Bohemian period of the Thirty Years ' War and decisively influenced the fate of the Czech lands for the next 300 years . Prelude . In the early 17th Century most of the Bohemian estates , although under the dominion of the predominantly Roman Catholic Holy Roman Empire , had large Protestant populations , and had been granted rights and protections allowing them varying degrees of religious and political freedom . In 1617 , as Emperor Matthias lay dying , his cousin Ferdinand - a fiercely devout Roman Catholic and proponent of the Counter - reformation - was named his successor as Holy Roman Emperor and King of Bohemia . This led to deep consternation among many Bohemian Protestants , who feared not only the loss of their religious freedom , but also of their traditional semi - autonomy , under which many of the estates had separate , individual constitutions governing their relationship with the Empire , and where the King was elected by the local leaders . Ferdinand ( who would become Emperor Ferdinand II following Matthias ' death in 1619 ) saw Protestantism as inimical to the Empire , and wanted to impose absolutist rule on Bohemia while forcefully encouraging conversion to the Roman Catholic faith . He also hoped to reclaim church properties which had been seized by Protestants at the start of the Reformation decades earlier , and to do away with the Electorate - the body of princes who chose the Holy Roman Emperor and who had considerable power over Imperial policy . Particularly galling to Protestants were perceived violations of Emperor Rudolf II ' s 1609 Letter of Majesty , which had ensured religious freedom throughout Bohemia . In May , 1618 , wanting to air their grievances over this and other issues , a group of Bohemian noblemen met representatives of the Emperor at the royal castle in Prague ; the meeting ended with two of the representatives and their scribe being thrown out a high window and seriously injured . This incident , known as the Second Defenestration of Prague , triggered the Bohemian Revolt . In November 1619 , Elector Palatine Frederick V , who like many of the rebels was a Calvinist , was chosen as King of Bohemia by the Bohemian Electorate . Battle . In 1620 , now fully established as Emperor , Ferdinand II set out to conquer Bohemia and make an example of the rebels . King Frederick and his military commander , Prince Christian of Anhalt , had organized a Protestant army of 30 , 000 men ; Ferdinand countered with a force of 25 , 000 , many of them seasoned soldiers , under the capable leadership of Field Marshal Tilly , a Roman Catholic Spanish - Flemish nobleman . Tilly ' s army enjoyed the advantage of including two of the most successful military leaders in European history - Tilly himself and the future General Wallenstein . Tilly ' s force was made up of two distinct groups : Imperial troops commanded by Charles Bonaventure de Longueval , Count of Bucquoy , and soldiers of the German Catholic League , directly under Tilly . All of the armies of the day employed numerous mercenaries , including , by some definitions , Tilly himself . Serving with the Catholic League as an official observer was the future " father of modern philosophy " , René Descartes . After conquering most of western Bohemia , the Imperial army made for Prague , the Bohemian capital , then in rebel hands . The Bohemians attempted to block them by setting up defensive positions , which the Imperial army simply bypassed . Force - marching his men , Christian of Anhalt managed to get ahead of the Imperial army just before Prague . He thus gained an advantageous position on the " White Mountain " , actually a low plateau , but had little time to set up defensive works . Enthusiasm for joining battle was low on both sides . After the reverses of the previous several weeks , Christian of Anhalt ' s army had been reduced to about 15 , 000 men , with little prospect of victory ; the mercenaries on both sides had not been paid in months ; and with winter approaching , cold , wet , weather made for less than ideal combat conditions . On November 8 a small Imperial force was sent to probe the Protestant flank . To their surprise , the Bohemians retreated at their advance . Tilly quickly sent in reinforcements , and the Bohemian flank began to crumble . Anhalt tried to retrieve the situation by sending forward infantry and cavalry led by his son Christian II . The cavalry charged into the Imperial infantry , causing significant casualties , but Tilly countered with his own cavalry , forcing the Bohemian horsemen to retire . The Bohemian infantry , who were only now approaching the Imperial army , saw the cavalry retreating , at which they fired one volley at extreme range before retreating themselves . A small group of Imperial cavalry began circling the Protestant forces , driving them to the middle of the battlefield . With the Bohemian army already demoralized , company after company began retreating , most without having actually entered the battle . Tilly and his Imperial cavalrymen advanced with 2 , 000 Bavarian hussars , steadily pushing Protestant forces back to the Star Palace ( just west of Prague ) , where the rebels tried without success to establish a line of defense . The Battle of White Mountain was more a skirmish than a full - fledged battle . The Bohemian army was no match for the Emperor Ferdinand ' s troops . The actual battle lasted only an hour and left the Bohemian army in tatters . Some 4 , 000 Protestants were killed or captured , while Imperial losses amounted to only about 700 . Aftermath . With the Bohemian army destroyed , Tilly entered Prague and the revolt collapsed . King Frederick with his wife Elizabeth fled the country ( hence his nickname " the Winter King " ) , and many Bohemians welcomed the restoration of Roman Catholic rule . Forty - seven noble leaders of the insurrection were put on trial , and twenty - seven of them were executed in Prague ' s Old Town Square on what came to be called the " Day of Blood " . Amongst those executed were Kryštof Harant and Jan Jesenius . Today , 27 crosses have been laid into the cobblestones as a tribute to those victims . An estimated five - sixths of the Bohemian nobility went into exile soon after the Battle of White Mountain , and their properties were confiscated . Before the war about 151 , 000 farmsteads existed in the Lands of Bohemian Crown , while by the year 1648 only 50 , 000 remained . At the same time the number of inhabitants decreased from three million to only 800 , 000 . The Thirty Years War had only begun , and Bohemia was often the scene of much bloodshed . There remained a strong Protestant army in Silesia under the command of Johann Georg of Hohenzollern , Duke of Krnov , which continued fighting the Imperial army in Moravia and in what today is Slovakia until 1623 . In 1621 , the Emperor ordered all Calvinists and other non - Lutherans to leave the realm in three days or to convert to Roman Catholicism . The next year , he also ordered all Lutherans ( most of whom had not been involved in the revolt ) to convert or else leave the country . By 1627 , Archbishop Harrach of Prague and Jaroslav Borzita of Martinice set out to convert the heretics , as they were termed , by peaceful means ; most Bohemians converted , but a significant Protestant minority remained . Spanish troops , seeking to encircle their rebellious Dutch provinces , seized the Palatinate lands . With the prospect of Protestantism being overrun in Germany , Denmark entered the struggle . Sweden was to join the Protestant forces in 1630 .