The Battle of Saule took place on 22 September 1236 in the Šiauliai area in Lithuania, at which the Lithuanians crushed the army of the Livonian Order that had launched a crusade to their lands from Riga. The Brothers of the Sword who tried to return to Riga via Semigallia (Zemgale) were harried and killed by the Semigallians, a Baltic tribe that became part of the Latvian and Lithuanian nations which formed later on. The date of the Battle of Saule has been marked in Lithuania and Latvia since 22 September 2000, by decrees of the parliaments of the two countries, as the Day of Baltic Unity, with the aim of reminding Lithuanians and Latvians of their ethnic similarities, and to encourage the closeness of the two kindred nations and the Lithuanian and Latvian states. The first time Lithuania and Latvia intended to commemorate the Battle of Saule together was in 1936, the 700th anniversary of the battle. However, the attempt to organise a shared celebration of the anniversary of the battle failed. This article seeks to answer the following questions: what prompted Latvia and Lithuania to organise the commemoration of the Battle of Saule in 1936; what were the meanings that accompanied the imagery of the Battle of Saule at the time; and why did the joint anniversary celebration not take place?