 On 5 March , the Red Army advanced 10 to 15 km ( 6 @.@ 2 to 9 @.@ 3 mi ) past the Mannerheim Line and entered the suburbs of Viipuri . That same day , the Red Army established a beachhead on the western Gulf of Viipuri . The Finns proposed an armistice on that day , but the Soviets , wanting to keep the pressure on the Finnish government , declined the offer the next day . The Finnish peace delegation went to Moscow via Stockholm and arrived on 7 March . The Soviets made further demands as their military position was strong and improving . On 9 March , the Finnish military situation on the Karelian Isthmus was dire as troops were experiencing heavy casualties . In addition , artillery ammunition supplies were exhausted and weapons were wearing out . The Finnish government , noting that the hoped @-@ for Franco @-@ British military expedition would not arrive in time , as Norway and Sweden had not given the Allies right of passage , had little choice but to accept the Soviet terms . The formal peace treaty was signed in Moscow on 12 March . A cease @-@ fire took effect the next day at noon Leningrad time , 11 a.m. Helsinki time . 
