Nikolaev was a disaffected young man who’d come of age during the Revolution and latterly been expelled from the Party for his bad attitude. He took his frustration out on December 1, 1934, when he stalked into the (suspiciously unguarded) office of Kirov and shot him dead.
The victim was much the more consequential figure in this transaction — both in life, and in death. Kirov’s murder would stand as a Reichstag fire moment unleashing the darkest years of Stalinist purges.
Kirov was an old Bolshevik agitator from way back. Widely respected, he’d been the party boss of Leningrad for nearly a decade, and a few months before his murder was overwhelmingly elected to the Communist Party’s Central Committee at the party Congress.
He was also, perhaps, seen by anti-Stalin factions within the party as a potential pole of resistance to Stalin* — though his weight as an “opposition” figure has also grown with the hindsight knowledge of what came next.
Kirov’s assassination was a double gift to the Kremlin, for not only did it remove the impediment himself, it licensed a furious security crackdown against the “terrorists” who orchestrated it. Said terrorists conveniently turned out to be dozens upon dozens (and indirectly, thousands upon thousands) of officials whom Stalin found convenient to destroy. “Kirov was killed in Leningrad,” Bukharin remarked upon hearing the news. “Now Koba [Stalin] will shoot us all.”
Within weeks of the murder, the exiled Trotsky was coming to the same conclusion, and charged that the Kirov investigation’s purposes was
to terrorize completely all critics and oppositionists, and this time not by expulsion from the party, nor by depriving them of their daily bread, nor even by imprisonment or exile, but by the firing squad. To the terrorist act of Nikolaev, Stalin replies by redoubling the terror against the party.
Stalin personally oversaw the investigation, even personally interrogated Nikolaev. And no surprise: the investigation’s casualties multiplied with alacrity.
The first commissar who made it to the murder scene “fell out of a truck” the very next day. Nikolaev’s mother, wife, siblings, and other associates were all disappeared and executed. 104 prisoners already under lock and key at the time of Kirov’s murder were judged guilty of conspiring with the assassin and shot out of hand. (Source)
In January 1935, Stalin had his long-neutered old rivals Zinoviev and Kamenev** preposterously convicted for “moral responsibility” for Kirov’s murder. Though they weren’t death-sentenced directly for this “responsibility” their condemnation set them up for their fatal show trial the following year. (Which included public confessions of involvement in the Kirov affair.) Guilt in Kirov’s death would be routinely bolted onto the show trials of political opponents for the remainder of the 1930s.
Stalin mined this terrorism panic so nakedly and purged so widely that the belief that Stalin himself ordered Kirov’s murder has long predominated. This theory of Stalin’s master orchestration also happened to be very convenient (pdf) for the post-Stalin party; Khrushchev directly hinted at his predecessor’s complicity in the secret speech.
That theory remains highly contestable. Matthew Lenoe in particular has vigorously disputed the idea that Stalin ordered everything in his acclaimed The Kirov Murder and Soviet History; there’s an informative Q&A with Lenoe on the invaluable Sean’s Russia Blog here, and a podcast interview on the New Books Network here. For a bit of background on Lenoe’s research, click here.
* Foreshadowing the unwelcome independence Leningraders enjoyed post-World War II … until Stalin smashed it.
** Nikolaev, the disaffected party member, was a Leningrader himself. That meant that when he was still in the party, it was in Zinoviev’s Leningrad party, since that city happened to be Zinoviev’s base and stomping-ground. And that meant that he must ipso facto have been part of the “Zinovievite Opposition”.