1914
23 July - Austria sends ultimatum to Serbia
Serbia, believing it has Russian support, rejects part of the ultimatum and begins mobilization
28 July - Austria declares war on Serbia
31 July - Tsar orders partial mobilization directed at Austria. Russian General Staff informs him partial mobilization is not possible, and Russia can only mobilize against both Austria and Germany. After deep thought and prayer, the Tsar instead of ordering full mobilization (as he did in OTL), decides against mobilization and calls for an international peace conference.
1 August - Germany doesn't declare war on Russia... the decide instead this gives them more time to hit France first
3 August - Germany declares war on France...
Schlieffen Plan etc., violation of Belgian neutrality, Brtiain enters the war etc., BUT Russia (and Italy) remain neutral
Later...
The Germans still fail to take Paris, trench warfare etc. They still need to keep forces deployed in the East, just in case Russia enters the war later.
Breslau & Goeben may still reach Turkey, but they don't shell Odessa, so the Ottomans aren't in the war
Russia remains neutral, planning only to enter the war if it gets a big enough bribe from the Entente, or Entente victory looks imminent
1915 Fighting breaks out between Ottoman and Russia in Persia. Russia declares war on the Ottoman Empire
Italy joins the Entente... more trench warfare etc. in the West
1917 US joins the Entente
Russians make major advances in Anatolia. Turkish resistance begins to collapse.
1918 Constantinople falls to Russia
Germany strips Eastern border of troops for final offensive in the West. Major offensive causes panic in the West (however offensive fails in its objective of taking Paris)
Desparate Entente secretly offers to recognize Russian claims to pretty much the whole Ottoman Empire (except Kuwait, and guarantees regarding holy places), and to allow Russian gains in Persia, Manchuria. Mongolia, and East Turkestan (Western China) in return for Russian entry in the war.
Russia declares war on Germany and Austria, and makes rapid advances both. Both are also collapsing from blockade, starvation and internal strife. Cossacks are within sight of the outskirts of Berlin...when
11 November - Ceasefire.
A few days later, Tsar Nicholas II weeps tears of joy, and leaves his palace to great the cheering throng outside. A Bolshevik activist, Simon Ter-Petrossian, widely known as "Kamo", however lies in wait, and throws a bomb... killing Nicholas II (who is later sainted as a martyr by the Russian Orthodox church).
The 14 (15?) year old, Alexei succeeds to the throne, and is crowned in St Petersburg, and as his father would have wished, in Hagia Sophia (which is now a church again) in Constantinople.