The 'Battle of Tolvajärvi' was fought in Ladoga Karelia between Soviet and Finnish forces within the context of the 'Talvisota' winter war, and was Finland’s first major success in this conflict (12 December 1939).

The Finnish plan was to encircle the Soviet 139^th Division of three regiments under the command of Kombrig Nikolai I. Belyaev by means of a pair of pincer attacks over the frozen Hirvasjärvi and Tolvajärvi lakes. The northern attack, over the Hirvasjärvi lake, was to begin at 08.00 on 12 December and the southern attack would begin after the first had brought results. This was later changed and both attacks were scheduled for simultaneous starts at 08.00.

The Soviet main effort at this time was based on the delivery of a frontal assault with the 609^th Regiment and 364^th Regiment over the Tolvajärvi lake and into the positions of the Finnish 16^th Jääkäriprikaati (infantry regiment) near the village of Tolvajärvi while the 718^th Regiment, the Soviet division’s third element, made a 12.5-mile (20-km) flanking manoeuvre from the north through a thickly forested area into the Finnish rear.

Thick fog lay over the battle area, which had only one narrow unimproved rural muddy road toward Tolvajärvi: this road wound between some dozens of small lakes. Just before the start of the battle a major snow storm deposited some 16 to 20 in (40 to 50 cm) of snow over the area. As a result of the fog, air power played no part in the battle, and the presence of mud under the snow meant that many of the Soviet tanks and other vehicles became bogged and thus could play no realistic part in the battle and were then lost during the Soviet withdrawal.

The Finnish forces were those of Eversti Paavo Talvela’s Ryhmä 'Talvela' ('Talvela' group) of the IV Armeijakunta (corps), and totalled some 4,000 men of the 16^th Jalkaväkirykmentti, together with the Osasto 'Rjasjanen' (Detachment 'Rjasjanen') of four separate battalions and one battalion of the 6^th Tykisterinrykmentti (artillery regiment). The Finnish forces thus totalled seven infantry battalions and 30 pieces of artillery. The 16^th Jalkaväkirykmentti comprised men from the town of Tampere under the command of the town’s chief of police.

As noted above, the Soviet force was the 139^th Division (718^th, 609^th and 364^th Regiments) of Komdiv Ivan N. Khabarov’s 8^th Army. The Soviet force comprised nine infantry battalions, 60 pieces of artillery, one reconnaissance battalion, one signals battalion, one sapper battalion, 30 tanks and 376 aircraft.

The Finnish northern pincer, based on two infantry battalions, advanced on schedule and soon met Soviet resistance in the form of the 718^th Regiment, which was preparing to make its own attack on the Finnish flank. By 12.00, the Finnish troops had withdrawn to their own line, and although this attack did not meet its objectives, it did serve to prevent the 718^th Regiment from attacking the Finnish flank, and also from sending reinforcements to the south.

On the southern flank, while it was preparing to attack along the single road, the 2/16^th Jalkaväkirykmentti was interrupted by an attack delivery by the 609^th Regiment. Even so, the Finns were still able to attack after they received supporting artillery fire. The Finnish attack continued toward a hotel located on a thin isthmus between the two lakes. Eversti Aaro Pajari decided to commit his reserve in a pincer attack at the Soviet troops around the hotel. The hotel was captured, and in it were found a dead Soviet regimental commander and all the regiment’s papers.

The Finns withdrew over the lakes for the night. In the morning, Talvela demanded a new attack and the 139^th Division was pushed back, and between 20 and 22 December was destroyed around the Ägläjärvi lake, some 12.5 miles (20 km) to the east of the Tolvajärvi lake. Contact was also made with elements of the 75^th Division sent forward as reinforcements.

The Finnish losses had been more than 100 men killed 250 wounded. The Soviet losses are thought to have been more than 5,000 men killed and a large quantity of weapons and other equipment: the guns of two artillery batteries, anti-tank guns, some 20 tanks (including a number of T-26 machines) and 60 machine guns. The battle was an important offensive victory for the Finns and was very significant for the morale of the whole Finnish army. No major battles were fought in this region after this successful Finnish counterattack, and combat was thereafter limited to skirmishes and small-scale artillery duels. The Finns held the line to the end of the 'Talvisota'.

Two of the Finnish commanders were promoted on 18 December: Talvela was elevated from eversti to kenraalimajuri, and Pajari from everstiluutnantti to eversti. Belyaev was dismissed from command of the 139^th Division on 16 December, but retained his rank and on 6 June 1940, after re-attestation, became a general major in the new Soviet rank structure.