During one of them, the "dogs gone mad speech" was delivered. They were preceeded by similar actions regarding accusations of "wrecking" and targeted 
During one of them, the "dogs gone mad speech" was delivered. They were preceeded by similar actions regarding accusations of "wrecking" and targeted at the employees of the Metropolitan Vickers Electric Company. The last one finished off the "right opposition," while the first one charged sixteen people with conspiring to murder Kirov. NKVD agents used torture to secure confessions, leading to the death sentences for Kamenev, Zinovyev, Bukharin at the hands of prosecutor Andrey Vyshinsky. For 10 points, name these events which gave a public veneer of legitimacy to Stalin's campaign against political rivals.
During one of them, the "dogs gone mad speech" was delivered.
{show trials} [accept {purge trials}; accept anything along the lines of “trials of Stalin’s political opponents” that demonstrates knowledge]