Russia's role in World War I (known more commonly as "the Great War" before anybody appreciated that there would soon be a war of even greater magnitude and destruction) was a product of Czar Nicholas II's interest in both restricting Germany's ability to threaten Russia's status and, more importantly, of his ill-considered diplomatic efforts relative to the "great powers of Europe," Germany, Britain, France, and the Austro-Hungarian Empire. Family relationships involving the czar and Kaiser Wilhelm, who were cousins, were further established through the relationship of the czar's wife, Alexandra, to the Kaiser (they were both grandchildren of England's Queen Victoria). This complicated series of personal and geopolitical relationships helped ensure that any conflict that broke out involving any two of these countries would almost certainly expand to include others by virtue of similar linkages and strategic considerations.
Russia has long had a very close political, spiritual and cultural relationship to Serbia. When the latter was attacked by the Austro-Hungarian Empire following the assassination of Archduke Ferdinand on June 28, 1914, the czar felt compelled to come to the defense of Serbia despite the familial relationship between the czar and the Kaiser. Germany's alliance with the Austro-Hungarian Empire then brought all of these nations into conflict with each other. Russia would subsequently be bled, figuratively and literally, dry by the costs associated with its participation in the world war that followed. That cost, both in men and money, would seriously weaken a monarchy already weakened by internal political machinations, corruption, incompetence, and increasing pressure from the revolutionary movements that would succeed in removing it from power.
One of the leaders of that revolutionary movement, and a particularly ruthless one, was Joseph Dzejugazhvili, who would change his name to Joseph Stalin (for "man of steel"). Stalin was not shaped by the Russian Revolution; he was one of its architects, a crude Georgian national who would play down his ethnicity as he rose up the ranks of a Russian political movement. Along with Lenin, Trotsky, Bukharin, and others, Stalin played a major role in the political intrigues and subversive activities that helped bring down the Romanov Dynasty and replace it with the totalitarian system that would be imposed on the Russian, Urkainian, Lithuanian, Latvian and many other peoples.