Secondly another problem was the land. There was significant unrest in the country side by May 1917. The peasants were hungry for land and the collapse of central authority meant there was no one to stop them taking it. Furthermore the peasants believed they had a right to the land but wanted government approval to give legitimacy to their actions. However the liberals in the government were not willing to just give the land to the peasant but they were not opposed to land redistribution. They just wanted it to be done with the framework of law set down by the constituent assembly and they wanted the land owners to be compensated. Additionally they believed that land-free-for -all would lead to disintegration of the army as the peasant soldiers might go back to claim their shares. The peasants did not agree with this so as the summer wore on they began taking more land and anything else they could take from private estates. This was a huge problem as the people failed to realize that fundamental land reform could not be put off until the constituent assembly as the peasants were going to take the land regardless. This contributed hugely to the downfall of the Provisional Government as it was probably that such unrest would lead to revolution.
Thirdly the national minority demands were a problem as it emphasized the splits between the government. After the tsarist state collapsed the fins the Poles and even the Ukrainians began to demand things like outright independence and self-government. This outraged the Liberals as they thought it would be the first step towards the break-up of Russia. This problem combined with the problem of the army and the land meant that a huge group of people were upset/angry by the decisions of the government. This was potentially a great problem especially if the soldiers, peasants, and the national minorities united.
Fourthly the deteriorating economic situation in Russia was another reason for the overthrow of the Provisional government in the October revolution. Food shortages, unemployment, and high prices were a huge factor in bringing about the February revolution. This meant that if these problems carried on there was likely to be a second revolution. Workers were affected hugely by this as the shortages of fuel and raw materials led to factories cutting output or closing or laying off work, this led to inflation. Also food shortages were a problem as grain was not getting in from the countryside and the peasants were being extremely uncooperative. The governments sent out requisitioning brigades to the countryside to get grain however this just made the peasants more hostile. Furthermore as all the resources were channeled to the army as the war was still going on, disagreements between workers and employers increased. This was because the workers had expected social reform after the February revolution (higher wages, better conditions, and shorter hours) however their wages were just becoming worthless and nothing else improved. As a result strikes increased. This was another big problem for the government as they were unable to meet the needs of the people.
Fifthly, the increasing popularity of the Bolsheviks contributed to the revolution and the overthrow of the provisional government. The reason for this is that the Bolsheviks became the main focus for the masses dissatisfied with the government's performance. Part of the reason for this is that Lenin offered a radical different programme from that of the Provisional government and he moderate socialist leaders of the other parties. Also the Bolsheviks had not joined the coalition so could not be blamed for or associated with the weaknesses and failures of the provisional government.
The April thesis was very significant in the rise of popularity for the Bolsheviks party because it was this change in policy (outright opposition of government no cooperation and calling for the soviet power) that some people argue is why the Bolsheviks took over government. However the provisional government did act to suppress the Bolsheviks in some ways as it spread the rumor that Lenin was a German spy and closed down Bolsheviks newspapers. This forced Lenin into hiding.
Lastly, the Kornilov affair and its consequences. Kerensky had many problems that he had to deal to stabilize Russia. He thought that he needed dependable troops when facing the Bolsheviks so he appointed General Kornilov. Unfortunately Kornilov decided that he was going to seize control of the government and establish military control. Consequently when Kerensky found out he panicked and call upon the soviet to protect Petrograd form counter revolution so soldiers workers sailors prepared to defend the city. The Bolsheviks red guard appeared and Kerensky naively gave them weapons even thought they were the very reason he had sent for kornilov in the first place. In the end the troops were stopped and Kormilov arrested. However this ill-judged action completely ruined Kerensky's reputation. Even the Mensheviks and Socialist Revolutionary leaders were discredited by association and a mass of people completely distrusted the Kadets and other liberals. Soldiers murdered officers as the thought the kornilov affair was an officer's plot. The Bolsheviks regained support once again and were elected in huge numbers on to soviets. They took control of the Petrograd and the Moscow soviet.
After the Kornilov affair rumors began to circulate that Kerensky was going to leave Petrograd to the Germans. This was a huge problem as it allowed the soviets to set up a military revolutionary committee in case there was another attempted right-wing coup. This was dominated by Bolsheviks and controlled by Trotsky. Kerensky decided to recover the situation by closing down Bolsheviks newspapers and restricting the powers of the MRC and to raise bridges which linked workers district of Petrograd. This was a mistake as it just gave the Bolsheviks a reason for action,
To conclude there is not one single reason or a 'main reason' that led to the overthrow of the Provisional Government in the October revolution because it was many factors combined that resulted in the revolution. There was a revolution because so many groups (workers, soldiers, peasants, and national minorities) were united under the leadership of the Bolsheviks to fight and overthrow the government. The war was not the main reason however it was a significant reason as it could be argued that if there had been no war that there may not have been as many food shortages as the peasants who were previously soldiers could have returned back to the country and grown more crops. Also it could be argued that the war was the main reason for conflicting opinions in the government anyway and without a united government the provisional government was doomed from the beginning. However many of the other reasons such as the Kornilov affair could be said to have been the main reason as maybe if it hadn't happened Kerensky would not have lost so much support. So I think that the continuation of the war was quite significant in causing the downfall of the Provisional Government however it was not the main reason as without all of the other factors I doubt that the revolution would have happened at that time.
