The Bolsheviks managed to gain power by a number of reasons.
The strong leadership of Lenin and his ability to read the publics collective mind brought the Bolsheviks support, leading them on their way to power.
Lenin was a skilled orator and could hold the rapt attention of large crowds. His speeches consisted of promises to the Russian people such as the April Theses, where Lenin promised "peace,land and bread". He also intended to redistribute land to the peasants and pull out of the war, something the Russian public had wanted for a long time. These were particular failures of the Provisional Government, and Lenin used them to his advantage. Peasants made up a large percentage of the Russian population, and the small plots of land given to them were insufficient and cripplingly expensive. The Bolsheviks gained popularity by promising to make dramatic changes,criticising the current Provisional Government.
WW1 had left Russia in physical and economical deastation.
Under the command of the Tsar, the army had suffered many humiliating defeats and over a million men had died. Families were desperate for the army to return, and men were needed in Russia to take factory jobs,as industry and production had come to a near stand-still, and in a particularly bitter winter, famine was sweeping Petrograd. Lenin's promise of the end of war seemed even more appealing.
People were unhappy with the Provisional Government already due to the bad and unfair living and working conditions in Russia. Mant houses were dirty and seriously overcrowded, and employers were allowed to over-work employees for as long as they wanted. Again, the Bolsheviks offered the change the public desperately wanted, as indicated by the July Days riots( people were seriously unsatisfied with present Russia). The Provisional Government had shown its own weakness when they called upon the Red Army to stop the Kornilov Revolt. Not only had the army also abandoned them,the Provisional Government had shown they were incapable of keeping control.
The final part of the Bolsheviks' succession to power was the careful planning of the October/November revolution in 1917, helped immensely by the support of the Russian army, the Red Army and several artillery factories. trotsky-leader of the Red Army-and Lenin planned the takeover of key buildings and communication centres in Petrograd and Moscow, stopping all people and infomation entering or leaving the cities. The Bolsheviks then invaded the Winter Palace, where the Provisional Government surrendered. This revolution not only gave the Bolsheviks complete power over Russia's major cities, but also showed the strong organisation and leadersip initiative of Lenin(and Trotsky) amid the chaos of Russia under the Provisional Government The October/November revolution, along with Lenin's leadership, the weaknesses of the Provisional Government, the poor state of Russia and World War 1 brought the Bolsheviks more support from the desperate Russian public, and with good timing they used this to eventually gain support in 1917