The reason for Russia entering the war was three-fold. One reason was that Russia owed Serbia allegiance, another being the loss of the Russo-Japanese war and the last, and arguably the most important, reason for Russia’s entry is the incompetence of the Czar.
The first reason for Russia entering the war was their allegiance to Serbia. Russia owed Serbia allegiance so when Austria declared was, it was Russia’s duty to fight with Serbia. Russia did this because the Serbians were all Slavophiles. This was important to the Russians as they were Slav as well.
The second reason for Russia entering the World War was the loss of the Russo-Japanese. Nicholas II was the first Russian Czar to lose land instead
of expanding, like the Czar’s before him who were all expansionists. This is important in the entry to World War One because it meant that Russia had a chance to redeem themselves of the embarrassment of that loss, of Port Arthur and the twenty-five ships. The Czar entered the war to try and make up for his loss of territory in his warm water Port Arthur and so thought he would gain some land in the war. As Russia had only ever lost the Russo-Japanese war, Czar Nicholas assumed he would do well in this war. This is important as it lead to ignorance from the Czar in the war scheming. This is shown in the fact he had 2 different commanders in the war cabinet even though a leader should only generally have one. The Czar’s incompetence and loss of the Russo-Japanese war is one of the factors that pushed him into the joining of the World War.
The last reason, and arguably the most important reason, for the Russians entering the war was the incompetence of Nicholas II in leading the Russian army and people.