The battle of Lake Peipus (mod. Peipsi Jarv, Estonia, Chudskoe Ozero, Russia) is more significant for its place in the national consciousness of Russia than as a military episode. In fact the battle itself was a small-scale affair, but it came to epitomize Russia’s struggle against Western interference. Similarly, the victory of a Russian Orthodox army over a force of Latin (i.e., Roman Catholic) crusaders became a symbol of the Orthodox determination to retain a distinct identity.
In the 1220s, as the Mongols attacked southern Russia, Danish and German crusaders conquered pagan Estonia. In response the Russians set about converting other Finno-Ugrian peoples to Orthodox Christianity. In addition to religious and political rivalry, there was also economic rivalry over access to Baltic trade. While the Mongols launched a second invasion of the south, friction increased between the newly established Baltic crusader territories and Russian Novgorod, culminating in the organization of a “Novgorod Crusade” in 1237. However, an invasion of Novgorodian territory in 1240-1241 faltered when Prince Alexander Yaroslavich of Novgorod defeated the Swedes at the River Neva, from which he was later known as “Nevskii.”
Prince Alexander now launched a counteroffensive, which culminated in a battle on the eastern shore of the frozen Lake Peipus. Here Alexander’s army, possibly supported by a contingent of Mongols, defeated a force of German crusaders from Livonia, Danes from Northern Estonia, and Estonian tribal auxiliaries under the command of the bishop of Dorpat.
It seems that the crusaders were pursuing the Russians, who had been raiding crusader territory. The latter retreated across Lake Peipus before adopting a defensive position on the far shore. A charge by the heavily armoured crusader knights was expected to break the enemy line, but instead the Russians absorbed the shock and attacked the crusaders’ flanks. Part of the crusader vanguard, including members of the recently disbanded Order of the Sword Brethren who had been absorbed into the Teutonic Order, was virtually wiped out, while the rest of the crusader army fled across the ice. Whether or not the ice gave way is unknown, although this did become part of Russian folklore.
Defeat at Lake Peipus undermined crusader prestige, contributing to an uprising by Estonians against Danish rule and by Prussians against the Teutonic Knights. In 1246 Prince Alexander submitted to the Mongol Great Khan, and six years later, with Mongol approval, he became grand prince of all Russia under Mongol overlordship.