Ladislaus IV of Hungary and Rudolf I of Germany defeat Ottokar II of Bohemia in the Battle on the Marchfeld near Dürnkrut in (then) Moravia.
The Battle on the Marchfeld (i.e. Morava Field; German: Schlacht auf dem Marchfeld; Czech: Bitva na Moravskm poli; Hungarian: Morvamezei csata) at Drnkrut and Jedenspeigen took place on 26 August 1278 and was a decisive event for the history of Central Europe for the following centuries. The opponents were a Bohemian (Czech) army led by the Pemyslid king Ottokar II of Bohemia and the German army under the German king Rudolph I of Habsburg in alliance with King Ladislaus IV of Hungary. With 15,300 mounted troops, it was one of the largest cavalry battles in Central Europe during the Middle Ages. The Hungarian cavalry played a significant role in the outcome of the battle.
King Ottokar II of Bohemia expanded his territories considerably from 1250 to 1273, but suffered a devastating defeat in November 1276, when the newly elected German king Rudolph I of Habsburg imposed the Imperial ban on Ottokar, declaring him an outlaw and took over Ottokar's holdings in Austria, Carinthia, Carniola, and Styria. Ottokar was reduced to his possessions in Bohemia and Moravia, but was determined to regain his dominions, power, and influence. In 1278 he invaded Austria, where parts of the local population, especially in Vienna, resented Habsburg rule. Rudolf allied himself with King Ladislaus IV of Hungary and mustered forces for a decisive confrontation.
Ottokar abandoned his siege of Laa an der Thaya and advanced to meet the allies near Drnkrut, north of Vienna. Both armies were composed purely of cavalry and were divided into three divisions that attacked the enemy piecemeal. In the first phase of the battle, the Cuman horse archers in the Hungarian army outflanked and distracted the Bohemian left flank by launching arrows while the Hungarian light cavalry crashed into the Bohemians, driving them from the field. In the second phase, a great collision of knights and heavy cavalry took place in the center, with Rudolf's forces being driven back. Rudolf's third division, led by the king personally, attacked and halted Ottokar's charge. Rudolf was unhorsed in the melee and nearly killed. At a decisive moment, a German cavalry force of 200 riders, commanded by Ulrich von Kapellen, ambushed and attacked the Bohemian right flank from the rear. Assailed from two directions at once, Ottokar's army disintegrated into a rout, and Ottokar himself was killed in the confusion and slaughter. The Cumans pursued and killed the fleeing Bohemians with impunity.
The battle marked the beginning of the ascendancy of the House of Habsburg in Austria and Central Europe. The influence of the Pemyslid kings of Bohemia was diminished and restricted to their inheritance in Bohemia and Moravia.
Ladislaus IV (Hungarian: IV. (Kun) László, Croatian: Ladislav IV. Kumanac, Slovak: Ladislav IV. Kumánsky; 5 August 1262 – 10 July 1290), also known as Ladislas the Cuman, was king of Hungary and Croatia from 1272 to 1290. His mother, Elizabeth, was the daughter of a chieftain from the pagan Cumans who had settled in Hungary. At the age of seven, he married Elisabeth (or Isabella), a daughter of King Charles I of Sicily. Ladislaus was only 10 when a rebellious lord, Joachim Gutkeled, kidnapped and imprisoned him.
Ladislaus was still a prisoner when his father Stephen V died on 6 August 1272. During his minority, many groupings of barons — primarily the Abas, Csáks, Kőszegis, and Gutkeleds — fought against each other for supreme power. Ladislaus was declared to be of age at an assembly of the prelates, barons, noblemen, and Cumans in 1277. He allied himself with Rudolf I of Germany against Ottokar II of Bohemia. His forces had a preeminent role in Rudolf's victory over Ottokar in the Battle on the Marchfeld on 26 August 1278.
However, Ladislaus could not restore royal power in Hungary. A papal legate, Philip, bishop of Fermo, came to Hungary to help Ladislaus consolidate his authority, but the prelate was shocked at the presence of thousands of pagan Cumans in Hungary. Ladislaus promised that he would force them to adopt a Christian lifestyle, but they refused to obey the legate's demands. Ladislaus decided to support the Cumans, for which Philip of Fermo excommunicated him. The Cumans imprisoned the legate, and the legate's partisans captured Ladislaus. In early 1280, Ladislaus agreed to persuade the Cumans to submit to the legate, but many Cumans preferred to leave Hungary.
Ladislaus vanquished a Cuman army that invaded Hungary in 1282. Hungary also survived a Mongol invasion in 1285. Ladislaus had, by that time, become so unpopular that many of his subjects accused him of inciting the Mongols to invade Hungary. After he imprisoned his wife in 1286, he lived with his Cuman mistresses. During the last years of his life, he wandered throughout the country with his Cuman allies, but he was unable to control the most powerful lords and bishops any more. Pope Nicholas IV planned to declare a crusade against him, but three Cuman assassins murdered Ladislaus.