The European expedition was to be a major Mongol effort, comparable in scope to the war against China. It was to become a catastrophe of monumental proportions for medieval East Europeans, who were confronted with devastating wars and serious social disruption. Nominal command was to be exercised by Batu, because this was the part of the world he had inherited from Chinggis. The actual commander was the aging, but still brilliant, Subetei. He was probably the most gifted of all Mongol generals, after Chinggis himself, and he had been one of the commanders of the momentous reconnaissance that had swept through southern Russia fifteen years earlier.

The Bulghars were defeated in 1236, and in December 1237 Subetei and Batu led an army of 600,000 across the frozen Volga River. The Mongols spread destruction and death through Russia. Moscow, Vladimir, and other northern Russian principalities were destroyed before summer 1238. Subetei then turned south to the steppe region around the Don, to allow his army to rest, to regain strength, and to prepare for new advances. Apparently his timetable was delayed for a year by a dispute between Batu and other royal princes commanding various hordes (see Glossary). Nonetheless, this additional time gave Subetei an opportunity to accumulate still further information about central and western Europe from his spies.

In November 1240, after the rivers and marshes of what, in modern times, is the Ukraine had frozen enough to take the weight of cavalry, the Mongol army crossed the Dnieper River. On December 6, it conquered Kiev, the seat of the grand prince and the Metropolitan See of Rus'. Subetei continued westward, his army advancing, typically, on a broad front in three major columns.

To the north was the horde of Kaidu Khan, three tumen strong, protecting the right flank of the main body. Kaidu swept through Lithuania and Poland; on March 18 he destroyed the Polish army at Cracow. He detached a tumen to raid along the Baltic coast and with the remainder headed westward into Silesia. On April 9, 1241, at Liegnitz (Legnica, in Poland), the more disciplined Mongol army decisively defeated a numerically superior combined European army in a bitterly contested battle.

Meanwhile, a horde of three tumen under Kadan, another son of Ogedei, protected the southern flank and advanced through Transylvania, into the Danube Valley, and into Hungary. In midApril Kadan and Kaidu joined the main body--under Batu--in central Hungary.

Batu led the central force across the Carpathian Mountains in early April 1241, lured the army of King Bela IV of Hungary into battle at the Sajo River on April 11, and annihilated it. The Mongols then seized Pest, and they spent the rest of the year consolidating their control of Hungary east of the Danube River.

Late in 1241, the Mongols were ready to move again. In December the army crossed the frozen Danube. Scouting parties raided into northern Italy toward Venice and Treviso, and up the Danube toward Vienna. But suddenly the advance halted. Word had come, by way of the incredibly swift Mongol messenger service, that Ogedei had died on December 11.

The yasaq explicitly provided that after the death of the ruler all offspring of the house of Chinggis Khan, wherever they might be, must return to Mongolia to take part in the election of the new khan. From the outskirts of Vienna and Venice, the tumen countermarched, never to reappear. They moved through Dalmatia and Serbia, then eastward where they virtually destroyed the kingdoms of Serbia and Bulgaria before crossing the lower Danube. They evacuated Hungary for lack of sufficient pasture and moved into the south Russian steppe. Advances into India also ceased.

Data as of June 1989