The invasion into Eastern Europe c. 1241 was a two-pronged attack. One regiment headed towards Poland and the other marched on to Germany. One of the regiments took Silesia, part of Poland at the time, and the other moved on to Hungary. The regiment that attacked Hungary took the Hungarian territory in the Battle of River Sajo. The grassy pastures of Hungary were optimal for the Mongols who boasted five horses per warrior. It was assumed that Hungary would be absorbed into the Mongol Empire. After the defeat of Hungary the path to Vienna was clear and ready for the taking.
In regular Mongol fashion they did not immediately attack the city. Rather, the Mongols picked off the outlaying districts instilling fear and panic in the residents. Unlike the Mongols numerous other successful implementation of this strategy, the farthest the Mongol regiment got in attacking Vienna was Wiener Neustadt, which was located just south of Vienna.
During a skirmish at Wiener Neustadt the Hapsburg troops captured, someone who they presumed was a Mongol officer. In reality they captured a thirty year-old Englishman. The Englishman had a knack for translating languages; fleeing persecution from the Roman Catholic Church ended up in the service of the Mongols. The presence of an Englishman with the assumed barbaric Mongols made the Hapsburgs rethink their judgments of the Mongols. However, the Hapsburgs killed the Englishman before they could find out what the Mongols had in store for Vienna.
Although the Mongols never literally penetrated Vienna, it was the last sizable and farthest Eastern European city the Mongols planned to attack. Therefore, Vienna marks the end of the Mongols in Eastern Europe. In addition to the capture and execution of the mysterious Englishman, by c. 1241, Genghis Khan’s sons had all died. Genghis’ grandsons raced back to Russia to fight over who would be named the next Great Khan. Also it was suggested that the climates and terrain beyond Hungary – damp, humid, forests, soft furrows – were not ideal for the Mongols. The Mongols never attacked the city of Vienna and the sought after full-scale invasion of Europe never happened. By c. 1242 the Mongol forces had withdrawn from western Europe and retreated back to Russia.