The battle of Suomussamli still stands as a testament to Finnish arms, as one reinforced Finnish division destroyed two Soviet divisions in a confused battle amid the frozen forests of central Finland. First the 163rd Rifle Division fell prey to the Finns and their ski tactics in late December 1939, and then the powerful 44th Motorized Rifle Division was trapped along the Raate Road in early January. Desperate to reopen the road to the 44th, the Soviet 9th Army sent its last reserve to re-establish contact. Near the village of Mantyla, the Finns were waiting.

The Finns ambushed the first battalion of the NKVD regiment, killing a large number of its men although Finnish accounts of "total destruction" appear to exaggerate this. Fierce fighting the developed which lasted past nightfall (thus putting the "total" part in doubt) before a final push brought the Finns to the Purasjoki bridge at 10 p.m. While troops from the 44th Motorized Rifle Division were stunned by the cold and the dark forests, the NKVD border guards had spent years in the region and had no special fear of the Finns or the terrain. Though many of the NKVD troops apparently know how to ski, Army command sent them forward in trucks and inadvertently limited rather than increase their mobility. Despite well-managed Soviet resistance, the Finns managed to blow up the bridge and isolate the 44th, which would soon be wiped out.