Warmatrix

The Battle of Suomussalmi, lasting more than a month in the winter of 1939 CE - 1940 CE, was part of the Winter War between the USSR and Finland. It is often hailed as an example of how lightly armed troops can defeat a superior enemy.
After the USSR had made a treaty with nazi Germany, its hands were free for military adventures. Eastern Poland was captured while the Germans took the west and the Baltic states were forced to accept Soviet military bases. The USSR wanted Finnish territory near Lake Ladoga and leases on Finnish ports, in exchange for some wasteland in northwest Russia. The Finns did not agree and negotiations led nowhere. The Soviets, with 3x as many soldiers, 30x aircraft and 100x tanks, decided to attack. They used a border incident as a casus belli and invaded in late november 1939 CE. Progress in the extreme north was rapid though later stalled and driven back; in the south the Finns conducted a fighting retreat to the Mannerheim line.
In the center the attack was aimed the village of Suomussalmi. The task was assigned to two divisions and one tank brigade, which had a combined total of some 50,000 men, 335 artillery guns, more than 100 tanks and 50 armored cars. The bad roads and weather slowed the Soviet advance to as little as 6 kilometers per day at times. Nonetheless Suomussalmi, which was defended by a single Finnish reserve battalion, was taken within a week. The Finns burned the village and retreated behind the neighboring frozen lakes Niskanselkrä and Haukiperä. The Soviets aimed to push further westward to Oulu on the Baltic coast and thus cut Finland in two halves. But their follow-up attack across the lakes failed, because on the ice their troops were easy pickings for the Finnish riflemen, machine guns and light anti-tank rifles. Often their tanks could not cross the lakes because the ice was too thin. The Finns were then reinforced by a jäger regiment to a total of 4,200 men. They tried to retake Suomussalmi, yet were repulsed in turn.
After the first days of battle, the fighting got less intense, while the Finns cautiously tried to pry open the Soviet lines. After two weeks the earlier ebb and flow of the battle was repeated: the Soviets once more tried to break through westward, again were stopped and again the Finns counterattacked. This time they managed to liberate Suomussalmi. This led to a retreat of the western Soviet division that got entangled with the other that was just coming up from the east, having been held up by Finnish road blocks. The Finns, using a tactic that they called "motti", trapped the Soviet mechanized troops on the narrow roads, broke them up into small groups and destroyed them one by one. The Soviet troops were immobilized on the road, deprived of intelligence and supplies; their fighting prowess steadily declined, though they kept up resistance for days.
The Soviet army was stronger in theory, but weakened by inexperience and by Stalin's extensive purges among the officer corps. It had an overwhelming advantage in airplanes, tanks and other heavy weapons, but had a lot of trouble using them in the rugged terrain, made up of dense forest and marshes. Snow, clouds and only a few hours of sunlight per day hampered offensives in general and the air force in particular. The mostly inexperienced and unmotivated soldiers lacked winter clothing and camouflage, which were sorely missed in the severe winter of 1939 CE - 1940 CE. The Finns on the other hand were adequately equipped with winter tents, transported on sledges, though they had almost no heavy weapons. Well trained and defending their homeland, they fought fiercely, making good use of their mobile ski troops. They intercepted Soviet telephone communications, moved their troops freely around and struck where the Soviets were vulnerable, retreating equally swiftly when defenses stiffened. They made a point of attacking Soviet fields kitchens and supply columns, to deprive the Soviet soldiers of warm food, weakening and demoralizing them.
In the first week of January the Finns destroyed what was left of the Soviet troops. They captured dozens of tanks and field guns; several hundred trucks, cars, and tractors; some 300 machine guns; 6,000 rifles; more than 1,000 horses and many radios, greatly boosting their strength. The Soviets lost approximately 27,500 men, half of them through the cold rather than in battle. The Finns, who had increased their force from 4,000 to 14,000 during the battle, lost 2,700 men.
Finnish victories in the center and north were not enough to win the war. In early 1940 CE Josef Stalin appointed Semyon Timoshenko as commander, who managed to break through in southeastern Finland, though at high cost in lives. In May Finland sued for peace. The country was forced to yield to all earlier Soviet demands, however it retained its independence. When nazi Germany invaded the USSR in 1941 CE in Operation Barbarossa, the Finns assisted, but they were careful not to advance beyond their pre-Winter War border. Three years later the Soviets struck back, though quickly signed a peace treaty with Finland so that they could focus their attention on Germany.