The 'Battle of Tienhaara' was fought between Soviet and Finnish forces within the 'Jatkosota' continuation war to the north of Viipuri (22 June 1944).
After the Soviets had captured Viipuri (Vyborg in Russian) in the course of the 'Vyborg-Petrozavodsk Offensive Operation', the Finns concentrated their defence in the Tienhaara region which offered favourable terrain for defensive operations as the nearby waterway cut the already narrow battlefield into several islands.
The 'Vyborg=Petrozavodsk Offensive Operation' had been launched on 10 June and in matter of days broke through of the Finns' fortified defence lines in the southern part of the Karelian isthmus. On 20 June the Soviet advance was already at the gates of Viipuri. Eversti Armas Kemppi’s (from 22 June Eversti Yrjö Sora’s) Finnish 20th Prikaati had been transferred to defend the city, but it had been inadequately supplied and lacked effective anti-tank capability as it had neither 75-mm (2.95-in) PaK 40 anti-tank guns nor knowledge on how to use the few available Panzerfaust and Panzerschreck anti-tank weapons. The 20th Prikaat was not prepared to handle the Soviet armoured assault, led by the CVIII Corps' 90th Division supported by the 260th Separate Heavy Breakthrough Tank Regiment and the 1238th Self-Propelled Gun Regiment, and the brigade’s resistance crumbled swiftly with some of its men fleeing either in panic or under supposed orders to withdraw.
The 61st Jääkäriprikaati was a regiment of Swedish-domiciled Finns and volunteers from Sweden under the command of Everstiluutnantti Alpo Marttinen of Kenraalimajuri Alonzo Sundman’s 17th Divisioona arrived on the Karelian isthmus from Svir immediately after the loss of Viipuri. The regiment was deployed for the defence of Tienhaara, which was located along the coastal highway leading to the north from Viipuri toward inner Finland, on the shore of Kivisillansalmi, on June 22, and relieved exhausted troops. Having strong artillery support and support of the German warplanes of Oberstleutnant Kurt Kuhlmey’s Gefechtsverband 'Kuhlmey', the regiment was able to hold the Tienhaara region, including the Kivisillansalmi, against repeated attacks by the 90th and 372nd Divisions of the CVIII Corps supported by powerful artillery. At the conclusion of the battle on 23 June, Marttinen was promoted to eversti.
At this juncture the Soviet forces attempted to push to the north but failed to break through the Finnish lines. The commander of the Leningrad Front, Marshal Soverstogo Soyuza Leonid A. Govorov, decided that further attempts to cross the waterway would prove be too costly and time-consuming, and instead concentrated the bulk of his forces into the Juustila-Ihantala area, contributing to the events which led to fighting in Tali-Ihantala region. The Finnish forces held Tienhaara (now Seleznyovo) until the ceasefire in the end of 1944’s summer, but the village was accorded to the USSR in the Treaty of Paris in 1947.