The Great Stand on the Ugra River () or the Standing on the Ugra River, also known as the Battle of the Ugra, was a standoff between the forces of Akhmat Khan of the Great Horde, and Grand Prince Ivan III of the Grand Duchy of Moscow in 1480 on the banks of the Ugra River. After Ivan III stopped paying tribute to the Horde, Akhmat Khan led an army to the river, which ended when both armies departed without conflict. In traditional Russian historiography, it has been interpreted as the end of the "Tatar yoke" in Russia, though some historians believe that the event itself was insignificant and did not change Russo-Tatar relations. Nevertheless, the event is usually regarded as the end of nominal Tatar suzerainty over Russia. Background The main Russian defence line ran along the Oka River from Kaluga east toward Nizhny Novgorod. At Kaluga the Oka bends sharply from north to east and the defense line was extended westward along the Ugra River. The land west and south of Kaluga was claimed by Lithuania. At this time Ivan III was uniting the lands north of the Oka. At the same time the Golden Horde was breaking up and the steppe remnant came to be called the Great Horde. Casimir IV Jagiellon of Poland-Lithuania was allied with the Great Horde, while Russia was allied with Crimea against the Horde. In 1472 Akhmed of the Great Horde raided the Oka at Aleksin but was driven off. In 1476 Russia officially stopped paying tribute to the Tatars. In late 1479 Ivan quarreled with his brothers, Andrey Bolshoy and Boris of Volotsk, who began intriguing with Casimir. This internal conflict may have influenced Akhmed's decision to attack. Campaign In late May news of the pending invasion reached Moscow. Nesin (2015) says it was the largest Tatar army in the fifteenth century. One faction wanted to flee north, but was overruled. In June Ivan sent troops south to the Oka: to Serpukhov under his son Ivan the Young, to Tarusa under his brother Andrey the Less and Ivan himself to Kolomna. Tatar scouting parties soon appeared south of the Oka. Russian outposts reported that Akhmed was tending northwest so Russian troops were moved west toward Kaluga. Forces from Tver moved toward the Ugra. Around 30 September (date uncertain) Ivan returned to Moscow to meet with his bishops and boyars and major