On 1 June 2000, President Vaira Vīķe-Freiberga promulgated in Riga amendments to the law “On Holidays and Remembrance Days,” which added 22 September – Baltic Unity Day – to Latvia’s official calendar. It linked modern Latvia and Lithuania to the memory of the 1236 Battle of Saule: a story of Baltic tribes’ joint resistance to the Livonian Brothers of the Sword and the idea that Latvian–Lithuanian kinship is not only linguistic, but also historical and political.

The establishment of Baltic Unity Day came at a time when Latvia and Lithuania were strengthening bilateral cooperation and moving together toward the European Union and NATO. The remembrance day turned the medieval memory of the Battle of Saule into a modern symbol of Baltic solidarity.