What was a major consequence of the Bolshevik Revolution under Lenin's leadership?

The Bolshevik Revolution, which took place in 1917, led by Lenin and the Bolshevik Party, fundamentally altered the course of Russian history and had significant international implications. One of the major consequences of the Bolshevik Revolution was indeed the withdrawal of Russia from World War I. After the revolution, the new Soviet government faced a significant challenge in terms of internal stability and the devastation brought by the war. Lenin prioritized peace over continued conflict and sought to consolidate power domestically.

In March 1918, the Treaty of Brest-Litovsk was signed, officially ending Russia's participation in World War I. This withdrawal allowed the Bolshevik government to redirect resources and attention toward stabilizing the burgeoning Soviet state, albeit at the cost of significant territory and resources. This action not only reshaped the geopolitical landscape of Eastern Europe but also set the stage for the Soviet Union's future interactions with other nations.

The other options provided do not capture the immediate and significant consequences of the revolution in the same way. While the expansion of the Soviet Union did eventually occur, it was not a direct consequence of the Bolshevik Revolution itself. Similarly, the establishment of a parliamentary democracy is fundamentally at odds with the nature of the Bolshevik