The 'Battle of Kelja' was fought between Soviet and Finnish forces around the village of Kelja within the context of the 'Talvisota' winter war (25/27 December 1939).

In the weeks before the start of the main Soviet invasion of Finland, the whole of the Finnish defence sector near Taipale on the south-western side of Lake Ladoga had been under heavy shell fire and daily infantry attacks by elements of General Major Avksentii M. Gorodnyansky’s 13^th Army of nine infantry divisions and one tank brigade. These attacks had all been repulsed, primarily by the Finnish artillery. The infantry attacks had reached their climax on 17 December, and then came to an abrupt halt on the following day. However, the shelling increased in intensity, and lasted throughout the invasion. In the final days before the main attack, Finnish aerial reconnaissance reported the arrival of the Soviet 4^th Division, and ground patrols reported unusually high numbers of Soviet troops in the area.

The Soviet attack on the positions of Eversti Jussi Sihvo’s 10^th Divisioona began early in the morning of 25 December as Soviet soldiers crossed the iced-over Suvanto lake under the cover of darkness. With the help of densely falling snow, the attack achieved almost total surprise. The Soviets unleashed a massive artillery barrage on Patoniemi fort, away from the main attack at Kelja. As the first Soviet soldiers reached the south-western shore of the long but narrow Suvanto lake, their artillery support finally opened fire on the Finns' rear positions. This caused confusion about the size of the attack, especially among the men of the company defending the Soviet beach-head, who reported the attack as nothing unusual.

The Soviet forces established three beach-heads, at Patoniemi, Volossula and Kelja. Finnish artillery was able to repel the second and third waves of reinforcements, but single battalions had already landed in each of the three beach-heads.

In the Patoniemi sector, the Soviets had deployed heavy machine guns on the flanks of the Finnish defenders before the latter realised what was happening. Even so, the defenders were able to stall the attack long enough to alert their battalion headquarters. The Finnish command reacted swiftly, committing a reserve battalion to the defence, and within a few hours the majority of the attackers had been pushed back across the ice or destroyed. Sporadic resistance lasted until evening, however, before the area was finally cleared of the Soviet invaders.

The Volossula sector was put on alert after the regimental headquarters was informed of the Patoniemi landing. After reporting that there were no Soviet forces in sight, the local regiment was ordered to advance toward Patoniemi. However, Soviet troops then started to arrive on the shore and the Finns were forced to deal with this landing before advancing. The Finnish battalion sent to reinforce the company defending the beach was hit by an artillery barrage, but nevertheless reached the objective within an hour. When the battalion arrived, the Soviets were already starting to dig in. Intense fighting ensued, and the Soviets were pushed back across the ice with heavy casualties.

In the Kelja sector, the commander of the local Finnish battalion received reports of Soviet forces crossing the ice. Finnish artillery opened up an immediate response and prevented the left wing of the attack from reaching the shore. By the time the battalion reserves could be mobilised, the rest of the attacking Soviet force was already at the edge of the shore near Kelja. Aided by an artillery barrage, the Finnish counterattack managed to push the Soviets back to the edge of the forest, where the Soviet troops dug in and managed to repel another counterattack in fighting which lasted throughout the day.

Throughout 26 December, the Soviets attempted to reinforce their beach-head with troops sent across the ice, but most of these were repulsed by Finnish artillery. Two more Finnish counterattacks against the dug-in Soviet positions failed, however, as the situation became more serious. The Finnish command decided that an immediate and decisive attack was needed to remedy the situation. Early in the morning of 26 December, therefore, the Finnish attack began as a Finnish company advanced toward the Soviet positions. Without artillery support and the mortars they had been promised but not received, and under heavy Soviet fire, the Finns were forced to retreat.

Another attack, this time by two companies, began later in the same day. The attack made some gains in its early stages, but after using most of their ammunition and coming under a heavy artillery bombardment, the Finns were again forced to withdraw. The rest of the battalion was ordered to hold its positions and stop Soviet reinforcements from crossing the ice.

Throughout the night of 26/27 December, the Soviet 4^th Division made repeated attempts to reinforce its positions on the lake’s south-western shore, but in clear moonlight, all were repulsed by the Finnish artillery. Almost a full regiment was committed in these attacks, which were disastrously costly to the Soviets. Finnish observers reported that 'the ice is littered with piles of bodies'.

On 27 December, the Finns launched yet another counterattack after the Soviets had once more been subjected to an artillery bombardment. This attack failed, once again, as a result of heavy machine gun fire, and the Finns were forced to withdraw. Then, later in the same day, another counterattack with more artillery support was launched. This was finally successful, as the battered Finnish company managed to infiltrate the Soviet positions. After over seven hours of continuous fighting, the Soviet resistance collapsed, although only at great cost. By the morning of 28 December, the area had been entirely cleared of the Soviets, and the 'Battle of Kelja' was over.

Although the Soviet attack had eventually failed, it did succeed in draining the Taipale sector of its Finnish reserves. The Finns were so short on manpower that reserves from the western sector of the Karelian isthmus had to be redeployed to Taipale, further weakening the isthmus area. However, the Finnish victory had the benefit of the Finnish seizure of much desperately needed Soviet equipment, including 12 anti-tank guns, 140 machine guns, 200 light machine guns and 1,500 rifles.