In June 1940, Lithuania, along with its Baltic neighbors, faced immense pressure from the Soviet Union amidst the geopolitical upheaval caused by World War II. On June 15th, the Soviets issued an ultimatum demanding the stationing of troops within Lithuanian borders, which was presented alongside promises of mutual assistance. The Lithuanian government struggled to respond effectively to this demand, and by the next day, they resigned under the threat of military intervention.

As a result, a provisional Communist government was quickly established, heavily influenced and supported by Soviet authorities. The new regime began implementing policies that aligned with Marxist-Leninist principles. Political purges ensued, targeting previous government officials, military leaders, and intellectuals who opposed Soviet rule. The nation became a republic within the Soviet Union, officially known as the Lithuanian SSR.

This shift marked Lithuania's entry into a Soviet-controlled period that would last until World War II reshaped the region again. The consequences of this transition included severe repression, mass deportations, and the suppression of cultural identity as Lithuania was integrated into the Soviet framework. The regime's actions signaled the start of a long and tumultuous relationship with Soviet power that had lasting effects on Lithuania's social, political, and cultural fabric.