The Battle of Kelja was a significant engagement during the Winter War between Finland and the Soviet Union. Initiated after Soviet forces invaded Finland on November 30, 1939, the conflict stemmed from Soviet desires to acquire Finnish territory, ostensibly for security reasons. By December, the Finnish defenders had positioned themselves strategically in the region of Kelja, preparing for potential assaults from the advancing Soviet Army. The Finnish military, primarily composed of hastily organized reserves and volunteers, capitalized on their extensive knowledge of the local terrain, which allowed them to implement effective guerrilla tactics and ambush strategies against the numerically superior Soviet forces.

As the Soviet troops approached Kelja, they faced severe winter conditions and logistical challenges that hampered their advance. The Finnish troops, well-prepared for the harsh climate, leveraged these difficulties to their advantage. In a series of intense skirmishes, Finnish units utilized their superior mobility and local knowledge to strike at Soviet supply lines and communications, disrupting their operations. This led to disarray among Soviet forces, who were not used to such determined resistance and were significantly hampered by the freezing temperatures and snow-covered landscape.

The battle continued through the end of December, resulting in heavy casualties for the Soviet forces and proving that the Finnish military could effectively resist an invasion from a larger adversary. The tactical success at Kelja helped to bolster Finnish morale and exemplified the tenacity of their fighting strategy. Although the Soviets eventually managed to regroup and consolidate their forces, the events at Kelja showcased the fierce resistance that Finland would continue to mount throughout the Winter War.