In the turmoil of the 1905 Revolution, Tsar Nicholas II had initially planned to institute a military dictatorship, rather than implement the reforms being demanded by the October Manifesto; to this end, he turned to great uncle, Grand Duke Nicholas Nikolaevich, asking the highly respected general to step in as military dictator. Nikolaevich's response changed the course of history -- not only did he refuse, but he held a pistol to his head and threatened to pull the trigger if the Tsar did not endorse the reforms being put forward; Nicholas, seeing no other option, acquiesced. It was this decision that, at least for the short term, brought the Revolution of 1905 to a seemingly successful conclusion.
But what if it had not happened this way? What if, on raising his pistol, the gun had gone off, killing or injuring the Grand Duke? Or, alternately, what if Nikolaevich had not threatened suicide at all? Could Tsar Nichloas have still attempted to go with the military dictatorship route, choosing somebody else?
CONSOLIDATE: Additional thought -- though it's a few months before the noted PoD, we might also consider the assassination of the Tsar's uncle, Grand Duke Sergei Alexandrovich, shortly after his retirement as Governor General of Moscow; had he still been alive, could that have influenced said event?