Causes of the Great Terror
Historically, the Soviet secret police stopped short of terrorising the Communist party. But at the end of 1934, Stalin launched a wave of political terror that claimed a million lives and resulted in 12 million people being sent to forced-labour camps. Stalin had a number of reasons of pursuing this: 1) events inside the Com party persuaded him that many of his so-called comrades could no longer be trusted. 2) Stalins paranoia was fed by his secretive police system, finally renamed the NKVD. 3) the purges were bound up with his economic goals. 4) the purges allowed stalin to remove his political rivals.
Conclusion following causes/great terror beginning
The Communists had always used terror. But the Great Terror - something new. For the first time, political terror was inspired by the paranoia of the leader and also for the first time, attacked the ruling party. Terror under Stalin was an integral part in securing power over the Party, BY finally removing his rivals and those who had personally know Lenin, Stalins's version of socialism and vision of Party history remained UNCHALLENGED.