Treniota’s personal influence grows while Mindaugas concentrates on the conquest of Ruthenian lands, dispatching a large army to Bryansk, the northernmost of the Severian cities in the possession of the Chernigov Rurikids.

After Mikhail of Chernigov was murdered by the Mongols in 1246 and his capital was destroyed, his son had moved his seat to Bryansk.

Treniota and Mindaugas begin to pursue different priorities.

In the midst of these events, Mindaugas' wife Morta dies, and he expresses the wish to marry Morta’s sister, who is the wife of his ally Daumantas, Duke of Nalšia, a northern province of the Grand Duchy of Lithuania.

In retaliation, …

King Daniel of Galicia dies in 1284 and Shvarn, one of his sons, receives nominal overlordship over all of the Kingdom of Galicia–Volhynia as its duke.

Immediately, he mounts a major campaign against Poland, this time aiming for Lesser Poland.

However, although joint armies manage to plunder Skaryszew, Tarczek and Wiślica, this time the campaign is less successful and the allied Ruthenian and Lithuanian armies are repelled.

The Yotvingian auxiliaries are defeated by Bolesław V the Chaste at the Battle of Brańsk.

The Lithuanians, under the joint rulership of Kęstutis and Algirdas, conquer the former Kievan Rus' territory of Briansk in the upper Desna River valley in 1359.

Smolensk under its hereditary ruler, Yury of Smolensk, and his father-in-law, Oleg Korotopol of Ryazan, revolts from Lithuania, not long after the Lithuanian defeat at the Battle of the Voskla River, battle; the pro-Lithuanian boyars in Bryansk and ...

Alexander is a weak and lethargic prince so incapable of defending his possessions against the persistent attacks of the Muscovites that he had attempted to save them by a matrimonial compact.

However, the clear determination of Ivan to appropriate as much of Lithuania as possible, finally compels Alexander to take up arms against his father-in-law, renewing hostilities in May 1500, when Ivan III takes advantage of a planned Polish–Hungarian campaign against the Ottoman Empire.

While preoccupied with the Ottomans, Poland and Hungary will not provide assistance to Lithuania.

The pretext is the alleged religious intolerance to the Orthodox members of the Lithuanian court.

Helena is forbidden by her father Ivan III to convert to Catholicism and this provides numerous opportunities for Ivan III, as defender of all Orthodox, to interfere in Lithuanian affairs and rally Orthodox believers.

The Muscovites promptly overrun Lithuanian fortresses in Bryansk, …

…Bryansk in the summer of 1534.

...Bryansk, and other towns.

Both Russia and the Polish-Lithuanian Commonwealth are shaken by internal strife while many smaller factions thrive.

Polish Lisowczycy mercenaries, who had been essential in the defense of Smolensk in 1612, when most of regulars (wojsko kwarciane) mutinied and joined the konfederacja rohatynska, had been content to guard the Polish border against the Russian incursions for the next three years.

Aleksander Józef Lisowski gathers many outlaws in 1615, however, and invades Russia with six chorągiew of cavalry.

He besieges Bryansk and ...