It was part of the Winter War and was fought near the village of Summa (now Sokolinskoe) along the main road leading from Leningrad to Viipuri.

The Finns had built 41 reinforced concrete bunkers in the Summa area, and the defence line was stronger than elsewhere in the Karelian Isthmus.

However, the Finns had made mistakes in planning and nearby Munasuo swamp, east of Summa, had a kilometer wide gap in the line.

Early on, Soviet general Meretskov attempted draw Finnish forces away from Summa with a feint attack on Taipale sector.

The Soviets began their push on Summa on 17 December, utilizing 200 strike aircraft and a five-hour artillery barrage.

The Finns stood still in trenches and allowed the Soviet tanks to move behind the defence line on 19 December, as they did not have proper anti-tank weapons.

Soviet tanks cut-off behind the line aimlessly attacked Finnish strongpoints, but once these were eliminated the threat was over.

Only two Finnish battalions launched a counter-attack against two well supplied Soviet regiments that were equipped with armor and artillery.