Stalin

When the Russian Social-Democratic Workers Party split, Jughashvili chose the Bolsheviks over the Mensheviks who had a majority in the Caucasus. He survived in the underground for years but also spent considerable time under arrest, in exile, and escaping from distant corners of the Russian Empire. While his actions gained the notice of Bolshevik leader Vladimir Lenin and other Bolshevik politicians, because he spent years underground and far from their European exile, Jughashvili remained a relatively insignificant member of the Bolshevik Party faction.
In 1912, he first used the nom de guerre Stalin, from the Russian "steel". Stalin soon became editor of the Bolshevik newspaper and a member of the faction's Central Committee. He also completed his only significant pre-revolutionary writing, an essay about non-Russian nationalities of the empire.

Receiving word of the February Revolution, Stalin and his fellow revolutionaries departed their Siberian exile for Petrograd. There, as part of Vladimir Lenin's close circle (and as a Central Committee member) Stalin participated--albeit largely behind the scenes--in events leading to the October Revolution of 1917. In the initial Council of People's Commissars, Stalin became Commissar of Nationalities because his non-Russian background gave him advantages in the important task of recruiting non-Russian nationalities into the revolutionary cause.
Stalin also became a party overseer of Red Army operations, a capacity in which he stood out for his excessive aggression in military strategy and zealous prosecution of purported counterrevolutionaries. These facts, capped by battlefield failures, first brought him into conflict with Leon Trotsky, the Party's military commissar. At the close of the Russian Civil War in 1922, Stalin became General Secretary of the Communist Party, an office future rivals initially dismissed as a mere bureaucratic post. Exploiting his authority over personnel, Stalin built up patronage networks of loyal party and government functionaries. Stalin's complex relationship with Vladimir Lenin came to a head in 1922 when the duo clashed over the legal framework for Soviet Russia's relationship with its non-Russian borderlands that were being incorporated into the new Soviet Union.
When Lenin died in 1924, Stalin overcame the leader's disparaging comments, and then cast himself as Lenin's most loyal disciple and interpreter. In the fierce intra-party leadership struggles of the 1920s, Stalin used the prestige gained through patronage and skillful political maneuvering to defeat Leon Trotsky (and all other rivals) during the race to grasp power. First among equals by 1928, Stalin became the unquestioned leader of the Soviet Union.

For twenty-five years, Stalin towered above politics, life, and propaganda unlike any other figure in the world. The cult of Stalin required that all achievements--from scientific discoveries to happy childhoods--be attributed to Stalin's guidance and inspiration. The industrialization campaigns of the Five-Year Plans before World War II were burnished with Stalin's image. All the while, any discussion of the accompanying famine, repression, and political turmoil of that period was ruthlessly repressed. To reinforce his power, Stalin used the secret police, an apparatus of which he retained close control. Fed by his own suspicions and fueled by police reports of suspected counter-revolutionaries, Stalin and his inner circle transformed a repressive system of prisons and forced labor into one that, by 1936, became lethal on an unprecedented scale.
Stalin routinely feared internal and external threats, including the rise of fascism in Europe, and he tasked the secret police with eliminating entire categories of reputed enemies within the Soviet Union. Until Stalin called a halt in 1938, the Great Terror consigned an estimated 700,000 to summary execution and millions more to hard labor, including the wives and children of the condemned. 

When war with Germany came in 1941, the Soviet Union proved unprepared. Stalin's strategic choices, dating at least to the ill-fated 1939 non-aggression pact with Hitler, made a German surprise attack possible. Stalin's orders to counterattack at any price and to treat tactical retreat as cowardice resulted in millions of Red Army dead and captured. Only in 1942 and 1943 did Stalin allow commanders the flexibility to employ strategies permitting the Red Army to fight effectively. Stalin remained the final arbiter of military and economic strategy, however, while conducting foreign policy virtually autonomously. Most visibly, Stalin remained a symbol in propaganda for the country and its war effort, an oddity in light of his thick Georgian accent and unimposing physical appearance in real life. Although mistrusted by his wartime allies, Stalin reached the height of his global influence during the war. Imposing control over conquered territories of Europe and, after 1949, navigating a close but fraught relation with Mao Tse-tung, the Soviet leader influenced the lives of one-third of humanity. In 1945, Stalin reversed the wartime expedient of relaxing his control over people and decision-making, re-imposing harsh discipline to gird state and society for the looming Cold War struggle. He surrounded himself with handpicked underlings, each of whom owed everything to him and yet could be-- and sometimes were-- eliminated at any moment. Repression continued after the war, including a campaign against prominent cultural and political figures. Only Stalin's physical decline hinted that change might someday come. As Stalin spent increasing periods recuperating in his villa on the Black Sea coast, age and health finally caught up to him in March 1953, when he died of a stroke. At the time, everyone, even those who had suffered under his rule, feared what a future might bring without the Great Leader who had led them through industrialization and a world war.

Suggested Reading and Resources:

Oleg Khlevniuk, Stalin: New Biography of a Dictator, trans. Nora S. Favorov (Yale University Press, 2015).

Stephen Kotkin, Stalin, vol. 1, Paradoxes of Power, 1878--1928 (Penguin, 2014).

Stephen Kotkin, Stalin, vol. 2, Waiting for Hitler, 1929--1941 (Penguin, 2017).

Stephen Kotkin, Stalin, vol. 3 (Penguin, Forthcoming).

Library of Congress, "Revelations from the Russian Archives,"https://www.loc.gov/exhibits/archives/intn.html