Battle of Saule The Battle of Saule ( ; ; ) was fought on September 22 , 1236 between the Livonian Brothers of the Sword and pagan Samogitians . Between 48 and 60 knights were killed , including the Livonian Master , Volkwin . It was the earliest large - scale defeat suffered by the orders in Baltic lands . The Sword - Brothers , the first Catholic military order established in the Baltic lands , was soundly defeated and its remnants accepted incorporation into the Teutonic Order in 1237 . The battle inspired rebellions among the Curonians , Semigallians , Selonians , Oeselians , tribes previously conquered by the Sword - Brothers . Some thirty years ' worth of conquests on the left bank of Daugava were lost . To commemorate the battle , in 2000 the Lithuanian and Latvian parliaments declared September 22 to be the Day of Baltic Unity . Background . The Sword - Brothers were established in 1202 in Riga to conquer and convert pagan Baltic tribes to Christianity . By the 1230s under the leadership of Master Volkwin , the Order was coping with strained financial resources , decreasing manpower , and ill reputation . The Order was in conflict with the papacy under Pope Gregory IX and the Holy Roman Emperor , two of its biggest supporters , over Estonia . However , on February 19 , 1236 , Pope Gregory IX issued a papal bull declaring a crusade against Lithuania . He targeted Samogitia , planning to conquer the coast of the Baltic Sea and connect with the Teutonic Knights in Prussia . The Sword - Brothers wanted to keep expanding along the Daugava River and was somewhat reluctant to march against Samogitia . In fall of 1236 a party of crusaders arrived from Holstein ; it demanded to be led into a battle . Volkwin gathered a large war party , which included troops from Pskov Republic , Livonians , Latgallians , Estonians . Events of the battle . The knights marched southward into Samogitia , raiding and plundering local settlements . The locals had only a few days to gather troops for defense . On the knights ' northward return , however , they encountered a determined group of Samogitians at a river crossing . Unwilling to risk losing their horses in the swampland , the Holsteiners refused to fight on foot , forcing the knights to camp for the night . The next morning , on the day of Saint Maurice , the main pagan forces , likely led by Duke Vykintas , arrived at the camp . The Lithuanian light cavalry flung javelins at short range , which were highly effective against the unwieldy Livonian heavy cavalry . The swampy terrain was advantageous for lightly armed pagans . The slaughter of the Christian troops , including Volkwin , sowed the seeds of confusion in the Livonian ranks . The lightly armed native forces under the command of the Brothers soon fled from the battle . Those crusaders and knights who tried to flee to Riga were allegedly killed by the Semigallians . Location . The exact location where the battle took place is unknown . The " Chronicum Livoniae " by Hermann de Wartberge mentioned that the battle was fought in " terram Sauleorum " . Traditionally , this was identified with Šiauliai ( , ) in Lithuania or with the small town of Vecsaule near Bauska in what is today southern Latvia . In 1965 the German historian Friedrich Benninghoven proposed Jauniūnai village in Joniškis district , Lithuania as the battle site . The theory gained some academic support and in 2010 the Lithuanian government sponsored construction of the memorial in Jauniūnai – a tall sundial , a pond , and a park of oaks . The village of Pamūšis , situated some east of Janiūnai on the Mūša River , also claims to be the location of the battle . " Saule / Saulė " means " the Sun " in both Latvian and Lithuanian .