By 1437 Khan Ulugh Muhammad lost the struggle for power in the Golden Horde. He was forced to flee and appeared with the small army near the town Belyov, which is in the upper reaches of the Oka River. Initially Grand Duke of MoscowVasily II, who was indebted to Ulugh Muhammad for the throne of the Grand Duchy, received fugitive Khan rather well and allowed him to nomadize in the vicinity of Belyov. There is evidence that Vasily II and Ulugh Muhammad concluded some kind of treaty, vowing not to commit hostile actions against each other. However, after the position of Ulugh Muhammad strengthened, he began plundering raids: "he ravaged foreign lands, like an eagle, flying far from his nest in search of food". This caused concern among people in the inner circles of Moscow Principality and they put pressure on Vasily II, so he decided to expel Ulugh Muhammad from Belyov. It is interesting to note that at that time the Grand Duke of Lithuania was formally suzerain of Belyov, like other Upper Oka Principalities, but they also retained their ties with Moscow.
1437 Campaign
Vasily II sent to Belyov an army under the command of his cousins Dmitry Shemyaka and Dmitry Krasny, and "many other princes". Russian sources estimate the army sent to Belyov as very numerous. On the way the army robbed local people, not only in order to feed themselves, but also sent the loot home. Going to spend the winter near Belyov, Ulugh Muhammad built near the town a kind of fortification – wicker walls were covered with snow and watered. After the water froze, a strong "ice fortress" was formed. The fortification was well located: from the West and South the approaches were protected by a deep ravine, along which the Belyovka River flowed, and from the East there was the steep bank of the Oka River. The gentle approach was only from the North, and at the narrowest point the passage was no more than 100 m wide.
Battle
On 4 DecemberRussian forces attacked the Tatars and drove them into the ice fortress, but were defeated trying to take it at once. Princes Pyotr Kuzminsky and Semyon Volynets, who broke into the fortification on the heels of the retreating Tatars, were killed. According to the Russian chronicle, the losses of the Tatars were also heavy, some unnamed Ulug Mohammed's son-in-law was even killed there. Instead of preparing for a coordinated assault, the Russian commanders entered into negotiations and lost their vigilance. In some chronicles, the main blame is assigned to Grigory Protasyev, voivode of Mtsensk, who allegedly sided with Ulug Mohammed and "made a treason". Protasyev reported that the Grand Duke wished to conclude peace and did not order "to fight with the Tsar". During the negotiations on the morning of5 December, Ulu-Mohammed refused to pay him any tribute and promised not to attack the Russian principalities, and offered his son as a hostage. In return, Ulu-Mohammad asked only to be allowed to remain near Belyov until spring. However, voivodes Vasily Sobakin and Andrei Goltyaev, who conducted the negotiations, rejected this proposal. Then Ulug Mohammed, who found himself in a desperate situation, personally led the attack on the Russian army. Taking advantage of the "great mist" the Tatars made the turning movement and attacked from the rear of the unprepared Russian troops. There was panic and total flight, and thus Ulug Mohammed won a complete victory.
Aftermath
After the defeat at Belyov, Vasily II together with Dmitry Shemyaka and Dmitry Krasny signed a treaty with Boris Aleksandrovich, Grand Prince of Tver, envisaging, in particular, mutual aid in case of invasion of "Tsar" or other Tatars. In return, Vasily and his cousins promised not to accept the cityTver and Kashin from the Tatars. Ulug Mohammed after the victory at Belyov captured the desolate city ofKazan, strengthened there and founded the Khanate of Kazan, and soon began raids on Russia.
