Zinov'yev and Kamenev, Stalin's former political partners, received prison sentences for their alleged role in Kirov's murder. At the same time, the People's Commissariat for Internal Affairs (Narodnyy komissariat vnutrennikh del = NKVD), the secret police agency stepped up surveillance through its agents and informers and claimed to uncover anti-Soviet conspiracies among prominent long-term party members.
At three publicized show trials held in Moscow between 1936 and 1938, dozens of these Old Bolsheviks, including Zinov'yev, Kamenev, and Bukharin, confessed to improbable crimes against the Soviet state. Their confessions were quickly followed by execution. (The last of Stalin's old enemies, Trotsky, who supposedly had masterminded the conspiracies against Stalin from abroad, was murdered in Mexico in 1940, presumably by the NKVD.)
The reasons for the period of widespread purges, which became known as the Great Terror, remain unclear. Historians commonly say that Stalin created the terror out of a desire to push the population to carry out his intensive modernization program, or to put off society to suspend dissent, or simply out of paranoia. Whatever the causes, the purges must be viewed as having weakened the Soviet Union.
The arguments for it being a strong factor to his grasp on power are simple thou. Through the purges he was able to get rid of the opposition and there for create a government that was supporting him obviously giving him a vast political advantage. But also the secret police, NKVD, also had a large say in this because without them the actions of the purges could not have been taken because they applied the force for it to be successful.
Leading on from that there are the secret police and their role. The NVKD was among the most brutal, repressive, and inhumane police organisations of human history. The NKVD's duties, while multifaceted, included the administration of the gulag's and prison system, the police, internal affairs for the police, and served as the main apparatus for carrying out the purges and mass executions of Communists and innocent Soviet civilians in the 1930s.
June 17th, 1935, opened the flood gates of NKVD terror on the Soviet population. While the agency had gone through varying periods of repression in the past, nothing would compare for what was to come. The Council of People's Commissars decreed on this day that the NKVD, while needing consent of a prosecutor to make an arrest, were permitted to arrest members of the Soviet Government up to and including the Central Executive Committee. All such arrests had to be approved. This power would lead to .
During the NKVD's reign of terror (1930-1953), 786,098 Soviet people were executed, 3.5 million were imprisoned, and 2 million people died in prison and exile. The vast majority of executions - 681,692, or 87% of the total - came in 1937 and 1938, corresponding to the years the Soviet Government required the NKVD to fulfill a predetermined quota of arrests and executions. This quota indicated that each city in the country held several thousand "traitors" that must be found and executed.
The NKVD obviously were a major part of Stalins hold of power as without them, people would have been free to say and think what they wanted and if Stalin wanted people to idolise him, he would not have it that way. Also the NKVD were the force behind the majority of Stalins campaigns and policies as they were there to force home the ideas of Stalin otherwise the people were taken to labour camps or just simply shot.
Another major factor was propaganda and the cult of personality. By propaganda he made it seem that Russia was extremely successful and well equipped and organised. The ordinary Russian people seemed to love Stalin for some reason. They seemed to think that Russia was very successful, and would deny Stalin's wrong doings.
Propaganda would be supporting communist policies, and criticising his opponents. This changed the way that people thought, and so more people would support his cause. The cult of personality was where everyone loved Stalin, and believed him to be a great leader. They had virtually been brainwashed by propaganda, and no one ever spoke against Stalin because they were scared of him and what he would do to them. If everyone loves him, it isn't going to be hard to maintain power so really this turns into a giant circle for Stalin. People are convinced he’s the right man than they think he does no wrong then others follow.
Overall I see all these factors as major factors to Stalin’s grasp of power. The secret police helped Stalin with force and his economic policies helped Russia become a better off nation. But the most important factors were propaganda and the cult of personality and the show trials. This is because these spread fear into the nation enabling to keep control yet people loved him for what he did for Russia.
