Final answer:
Stalin used the assassination of Sergei Kirov as a pretext to consolidate his power and initiate the Great Purge, a campaign of political repression that solidified his control over the Soviet Union.
Step-by-step explanation:
The assassination of Sergei Kirov in 1934 was used by Stalin to consolidate his power and initiate the Great Purge. Kirov's assassination provided Stalin with a pretext to launch a massive campaign of political repression, which aimed at eliminating dissent within the Communist Party as well as in the wider Soviet society.
The Great Purge targeted not only perceived political opponents but also extended to the military and other sectors, leading to widespread executions and imprisonment. This period of terror solidified Stalin's dictatorship and increased his control over the Soviet Union, systematically removing any potential threats to his authority through brutal means.