In the late 12th century, the Hanseatic League colonized the upper Baltic around Livonia (modern day Estonia and Latvia), and began converting the pagan Finnic and Ugric peoples there to Christianity. They formed the crusading order The Swordbrothers of Livonia to forcibly convert the pagans. But after a serious defeat in 1236, the Livonian Order merged with another order, the Teutonic Knights.
The Teutonic Knights, who were the most dedicated to the Baltic Crusades (or Northern Crusades, as opposed to the earlier crusades in the Middle East) were themselves defeated by the Mongols along with their uneasy Polish allies at the Battle of Liegnitz in 1241. Checked in the south by the Mongols and the already Catholic Poles, the Teutonic Knights turned north to lands adjacent to their Livonian brothers, and sought to expand their conquests at the expense of the only Russian entity that did not fall to the Mongols, the merchant republic of Novgorod.
Novgorod was not Roman Catholic, but Eastern Orthodox and a legitimate, even preferred target for the Baltic Crusades. The mid-13th Century was the high point of the schism between Orthodoxy and Catholicism; the Fourth Crusade captured Constantinople in 1204 from the Byzantines and in 1242 the city and a large portion of the Byzantine Empire was still part of a Roman Catholic state ruled by a transplanted French born nobility. A Teutonic conquest of rich Novgorod would be a serious blow to the primacy of Orthodoxy in Eastern Europe.
However, Novgorod was led by the young and energetic Prince Alexander Nevsky, who even at the age of 21, was a proven battle leader and adept politician. As the last remaining unconquered Kievan Rus holding, he knew the Teutonic Knights would take advantage of its weakness and attack the city. With the main Mongols army temporarily stymied by the vast marshlands to the east, he gathered his militia, some Mongol mercenaries who were left behind and bored, and the households of his boyars, or nobles, and attacked Livonia in the west, before they could do the same to him.
The raiding into Livonia in the cold March of 1242 brought the Teutonic Knights out of their castles before many of the “summer soldiers” (the crusaders, adventurers, and mercenaries that arrived every spring to loot and rape their away across the Baltic until it got cold.) could arrive. Nonetheless, the Teutonic Knights could muster 100 heavily armored brothers (easily the best trained and best equipped knights in Eastern Europe at the time), 800 superior German and Danish knights, and about 1800 Estonian, German, and Danish infantry.
Nevsky greatly outnumbered the Teutonic Knights but most of his army was of much lower quality. His best troops were the druzhina, the body guards and household companions of the boyars. That thousand was (very) roughly equivalent to the German and Danish knights if a bit more eclectic and not nearly as disciplined. His most numerous troops were the city militia of Novgorod and Finnic-Ugric tribesmen who knew the Teutonic Knights all too well. Though unarmored for the most part, combined they were a formidable mass at nearly 3500 men. Finally, Nevsky had 600 Mongol horse archers.
When the Teutonic Knights attempted to put an end to the embarrassing raids, Nevsky withdrew. The Teutonic Knights assumed that although Nevsky greatly outnumbered them, the poor quality of his troops wouldn’t be able to withstand a charge by the heavily armored knights. But Nevsky was just executing the time honored Russian tactic of withdrawing until turning and facing their attacker on the ground of their own choosing (See every invasion of Russia ever). On 5 April, 1242, Nevsky stopped marching and formed on the east bank of the frozen Lake Peipus.
By withdrawing to the east bank of the frozen lake, the Teutonic Knights were forced to charge across the ice to reach the Russian army. Nevsky drew up his men in three ranks with the tribesmen in front, the city militia behind, and the cavalry in the third, screened by the first two. The knights thundered across the lake and charged directly at the Russian infantry. Their target was Nevsky, as the army would disintegrate without him. However, their slipping and sliding on the ice lessened the blow significantly. The tribesmen and militia held despite horrendous casualties. In many places the ice broke under the immense weight of the charging knights. Fortunately for them Lake Peipus was shallow at the point where the battle was fought, so they didn’t drown. But many knights found it difficult to maneuver in the freezing water up to their stirrups or even knees, whether while engaging the spear and polearm wielding infantry dancing about the unbroken ice, or attempting to force their way through the unbroken ice to engage the infantry on shore. The surviving accounts of the battle describe the knights growing exhausted just from killing infantry, but they never broke. Moreover, the Knights never got close to Nevsky: he commanded from a position behind where he could effectively direct the battle in the Eastern tradition, unlike the Teutonic commander who was in the thick of the melee.
Once the Knights were committed, Nevsky then released some of his cavalry to flank the Knights to the south, while the horse archers did the same to the north. He kept the cream of the druzhina to await a suitable moment for a devastating counterattack. The Teutonic Knights saw the maneuvers, but the ice and the numerous infantry kept them from responding effectively. The horse archers in the north were particularly effective as the lighter horses were much more nimble on the ice, and the heavily laden knights could not effectively come to grips with the Mongols, who picked off the Danish knights at their leisure. The northern flank of the Teutonic line broke.
Nevsky ordered the remaining druzhina to charge into the gap. The Teutonic Knights were surrounded, and it was clear to everyone on the “field” of battle that the Knights’ cause was lost. Individually, then in groups, they began to cut their way out. The infantry routed and “countless Estonians were killed”. In their haste many perished when they traversed patches of thinner ice to avoid the pursuers and plunged into the icy water, which was much deeper the further they were away from the eastern shore.
Alexander Nevsky’s victory at the Battle on the Ice ended the Teutonic Knights’ ambitions on Russian territory. Once the Mongol threat subsided, they would eventually turn on Lithuania and Poland. Ten years after the battle, Nevsky was crowned Grand Prince of Vladimir, the supreme ruler of all Russians, and in 1547, he was canonized by the Eastern Orthodox Church. In 1938, the campaign and battle was immortalized in Sergei Eisenstein’s Soviet propaganda film, “Alexander Nevsky” which became very popular during the Second World War, even though it was taken out of circulation when Nazi Germany and Stalin’s Soviet Union were allies between August 1939 and June 1941.