Final answer:
Stalin gained and maintained control in the USSR through a police state, censorship, propaganda, political purges, and centralized economic planning, leading to economic growth but severe repression and human rights abuses.
Step-by-step explanation:
Joseph Stalin secured and maintained absolute control in the Soviet Union through various strategies that resulted in profound changes in Soviet society, economy, and international relations. Using his position as General Secretary, Stalin controlled appointments within the Communist Party, ensuring loyalty and the consolidation of power. To achieve his vision of a socialist state, he employed propaganda, censorship, and extensive use of the secret police. These methods led to a pervasive climate of fear, epitomized by the 1930s 'purges' where numerous perceived opponents were executed or sent to gulags.
Soviet industrialization accelerated under Stalin's Five-Year Plans, which, despite their often devastating human cost, contributed to significant economic growth and the transformation of the Soviet Union into a major industrial power. Propaganda was also used to foster a cult of personality, presenting Stalin as the embodiment of the Revolution and the source of all Soviet achievements. While the economy grew, the society suffered due to heavy repression, lack of political freedom, and massive human rights violations.
Militarily, Stalin sought to protect the Soviet Union against external threats and achieved military prowess, establishing the USSR as a key global power. His economic policies, though brutal, provided full employment and were seen as successful, especially against the backdrop of the Great Depression in Western democracies.