The Swedish–Novgorodian Wars were a series of conflicts in the 12th and 13th centuries between the Novgorod Republic and medieval Sweden over control of the Gulf of Finland, an area vital to the Hanseatic League and part of the trade route from the Varangians to the Greeks. The Swedish attacks against Orthodox Russians had religious overtones, but before the 14th century there is no knowledge of official crusade bulls issued by the pope.
Background
Scandinavians maintained trade relations and other links with Novgorod from the Viking Age onwards. Merchants from Gotland operated both their own trading house (Gutagård) and Saint Olaf's Church in Novgorod. Scandinavians also carried out isolated raids on Novgorod. Eiríkr Hákonarson raided Ladoga in 997, and his brother Sveinn Hákonarson followed suit in 1015. After the marriage of Yaroslav I (Grand Prince of Novgorod and Kiev) to Ingegerd of Sweden in 1019, Ladoga became a jarldom in the orbit of Kievan Rus'. It was ruled by Ragnvald Ulfsson, the alleged father of King Stenkil of Sweden (reigned 1060–1066). Dynastic marriages took place between Russian and Scandinavian royal families—for example, in the 1090s Stenkil's granddaughter Christina married Mstislav of Novgorod, upon whose death in 1132 Novgorod seceded from Kievan Rus'.
The major turning point into more permanent conflict between Sweden and Novgorod arrived with Sweden's firmer organisation into the Catholic Church in the 12th century and papal involvement in crusades against lands controlled by the Orthodox church.
Fighting resumes
The 12th century is poorly documented in Sweden, and Russian documents are fragmentary. From the surviving sources, however, it seems evident that the newly founded republic and Sweden drifted into hostilities that could not be permanently settled ever again.
According to the Novgorod First Chronicle, the Swedish troops attacked the Novgorod merchants somewhere in the Baltic Sea region and killed 150 Novgorodians in 1142. It is the first known case of hostilities between Sweden and Novgorod. In 1164, a strong Swedish fleet approached Ladoga but was soundly defeated with most of its ships captured by Novgorod.
According to Swedish sources, the Novgorodians and their Karelian allies launched pirate raids against mainland Sweden during the 12th century. During one of such raid, they brought to Novgorod the gates of Sigtuna's cathedral as loot. In the eyes of the northern crusaders, such actions justified war against Novgorod, although Novgorodian sources do not mention these events. Swedish sources refer to the attackers of Sigtuna as "heathens". Swedish sources also document that Jon Jarl spent nine years fighting against Novgorodians and Ingrians at the end of the 12th century. These expeditions are not documented in Russian sources.
Battle of the Neva
After a long pause in open hostilities, Swedes purportedly undertook an attack against Novgorod in 1240. The only source of information on the attack is a Novgorodian chronicle. Soon after their fleet entered the mouth of the river Neva, the Swedes were roundly defeated in the Battle of the Neva by a young prince, Alexander of Novgorod, who would later be given the epithet "Nevsky" to memorialise this victory.
From then on, Sweden moved its interest to Finland. Its troops did not return to the Neva before the end of the 13th century, when it had gained some kind of hold of western Finland. Earlier, Swedes had also tried to establish a bridgehead in Estonia, in vain.
Focus moves to Finland
Apart from Ladoga, Novgorodian interests clashed with Sweden's in Finland, a region between Sweden and Russia which Russian forces sacked on numerous occasions from the 11th century onward. The raid in the winter of 1226–1227 led to heavy losses on the Finnish side. A Finnish retaliatory raid against Ladoga in 1228 ended in defeat, contributing to the Finns' subjugation by the Catholic Swedes during the Second Swedish Crusade in 1249. Seven years later, the Novgorodians devastated Swedish Finland again.
In 1293 the Swedes won a part of western Karelia and built the fortress of Viborg there. This expedition has traditionally been dubbed as the Third Swedish Crusade. Seven years later, they founded the fortress of Landskrona in the mouth of the Neva, on the river Okhta, and ruined the Novgorod settlements on the Neva. Later that year, the Novgorod troops retaliated by destroying Landskrona.