How did the Bolshevik movement begin?
The Bolsheviks split from the Russian Social and Democratic Labour Party in 1903, forming an entirely separate political party in 1912. The dispute that led to the split was over whether or not Russia should undergo a capitalist stage before it could become socialists, or, as the Bolsheviks thought, whether it could skip a stage of history. See: The Communist Party of the Soviet Union - Leonard Schapiro
How did the Bolsheviks come to power?
They came to power by seizing the seat of the Provisional Government - the Winter Palace - along with the main junctions, bridges, and communications centres, thus preventing the Provisional Government from mounting any counter attack. The Provisional Government was swamped by the the October Revolution because it lacked democratic legitimacy. The Provisional Government was the re-constituted last State Duma. It refused an election to a promised interim government - the Constituent Assembly - saying that Russia would hold elections after the war. The Petrograd Soviet was seen by many as a genuinely democratic institution, as it's members were elected to it from the garrisons and factories of the capital. The Bolshevik slogans "Bread, Land and Peace" and "All Power to the Soviets" sum up the other major factors: The cities were starving as the peasants were now in uniform fighting in the war - they could not plough, sow or harvest the crops. And the food delivery infrastructure had broken down. The peasants wanted the Provisional Government to give them the land they worked on - it didn't, and the most of the land was still owned by the aristocracy. And Russia was doing badly in the war and most people wanted Russia to withdraw from it. Soviets were seen as genuinely democratic bodies - they were mostly formed spontaneously and ran everything from factories to city blocks. By demanding All Power to the Soviets the Bolsheviks were tapping into popular democratic demands. Other factors: Lenin was a dedicated, determined and capable leader. He motivated his party and, through agitation & propaganda, the Bolsheviks became very popular in the army and in the factories. Trotsky was an extremely gifted administrator. He was the chairman of the Milrevkom - the Military Revolutionary Committee - this was the organisation that orchestrated the events of October 1917. The leadership of the party was loyal to Lenin, and they followed his orders with conviction. The party had a competent propaganda machine, producing newspapers, banners, posters and setting up recruitment drives in the army and factories. See: The Bolsheviks in Russian Society - Vladimir Brovkin The Russian Revolution - Sheila Fitzpatrick The October Revolution - Roy Medvedev http://www.soviethistory.org/index.php?p... http://www.marxists.org/history/ussr/eve...
What changes did the bolsheviks make to society?
Sorry, the answer HAS to be long, because the transformation of Russia under the Bolsheviks was very complex. Russia, from 1906 until February 1917 was an Imperialist, semi-capitalist, semi-feudal country, Lenin said that "Imperialism is the highest state of capitalism". From February 1917 until the Bolshevik takeover in October 1917 it was a capitalist country, with many feudal vestiges. Lenin, as a communist, sought to both remove the last traces of feudalism and to transform the capitalist elements of the economy into socialism. He did this by first (on the day after the the seizure of power) by granting the peasants the land - in reality he legalised what had been going on across the country since February 1917, as the peasants took the land from their landlords, burning manor houses and threatening - occasionally lynching - the landlords or their agents. Secondly he nationalised, without compensation, all the large factories, such as the Putilov Works in Petrograd and the iron and steel works of Yuzkova (now called Donetsk in Ukraine), all the banks and mines. This lasted until march 1918, when the civil war erupted in earnest. The war began to disrupt food supplies to the cities, as the peasants tried to get better prices for their grain. Lenin then began the policy known as War Communism - this was, basically, legalised theft, as armed communists went to the countryside to search, and seize, any surpluses they could find. Although the policy was successful, in that the cities and Red Army were fed, it had a disastrous effect on the economy, as peasants refused to sow their fields, and hid as much grain as they could. In 1921, as the Civil War was more or less won, War Communism needed to be replaced, more to reinvigorate the economy than for ideological reasons. War Communism was replaced by the New Economic Policy. See: http://www.soviethistory.org/index.php?p...
How did the bolsheviks win the civil war?
The Bolsheviks (the Reds) were better organised - Trotskii was a brilliant administrator and put the Red Army together. The Bolsheviks were concentrated in the Moscow / Petrograd heartland of Russia, so their support was urban and concentrated in a small, but (relatively) densely packed area. The Bolsheviks had, because of the concentration in cities, better communications. The Whites were never a unified military force, they were often as opposed to each other as they were to the Bolsheviks. Bolshevik agitation and propaganda in the Tsarist Army had led many soldiers to join the party, the Whites were often not military trained. The Bolsheviks had more capable commanders, capable of working with each other for strategic ends. In areas the Whites captured they acted as badly as the Reds, so local populations turned against them. See: The Russian Civil War 1918 - 1921 by David Bullock
How and why did the Bolsheviks gain power in Russia?
World War I caused economic disrupt, high inflation which hit lots of the simple people. Czar Ruble was originally was very stable and strong currency and now people savings become to disappear and food / service prices rised. Do not believe to pro-Czar propaganda which says about growth of industrial output. Yes there was growth of industrial output even during WWI in Russia. But one cannot eat a machine-tool or an engine.Modern Russians are used that Ruble is weak and falls often but for Czar people that was bigger shock because they were used to relay on it's stability.Bolsheviks smartly used this imperialist part of war for their internationalism propaganda. WWI was really ugly, indeed:Our famous commander George Zhukov was simple soldier at WWI. In his memories he remembers that rich elite mostly did not conscript but continued their luxury life in Moscow and St.Petersburg. While simple people had to die for imperialistic interests of elites. Not just in Russia, in another countries as well.Many of Old Bolsheviks were active non-Russian origin people. Czar Russia was portrayed as "jail of nations" which needs to be liberated from nationalist backwardish Czar oppression. Old Bolsheviks actually were pro-western liberals, but of very extreme left origin (everything "anti" - anti-capitalism, anti-communism is popular in Russia). It's a country which cannot find middle social-democratic ground. Like USA.For example advisers suggested to Nicholas II to fully emancipate Russian Jews. Czar was told that it would significantly reduce revolutionary sentiments among Jewish people. But Czar was too conservative and refused it.After failure of Decembrist revolt there was conservative reactionary movement in Russia lead by Nicholas I. While some Western countries evolved and developed rapidly in XIX century allowing them to reduce some of major social troubles, Russia struggled with serfdom until last part of XIX century, delaying it's development.In one sentence: delayed development in XIX century due to serfdom; lack of full emancipation; WWI.I am afraid that today Russia also does not handle it's problems well.
How did the Bolsheviks win the Russian Civil War (1918-22)?
As other answers put it, the opposition to Bolsheviks was fractured into multiple factions, sometimes with radically different agendas, that occasionally fought each other. Bolsheviks were the masters of Realpolitik, they would routinely exploit these differences by making an alliance with faction A, beating faction B with its help, and then calling the allience off and turning their weapons against faction A. Amazingly, in some cases they were able to switch sides several times, e.g. with getman Mahno.Bolsheviks were also quick to promise people what they wanted to hear, not necessarily meaning to act on those promises. To the peasants they promised land, to the workers they promised ownership of factories, to the nationalists they promised self determination, to everyone they promised all power to the elected councils (“soviets"), and the Establishing Congress (“Uchreditelnoe Sobraniye") that would adopt the Constitution and create new, elected government of the Russian Republic. None of that happened.Whites were less ideologically “flexible", e.g. the monarchists insisted on “United Russia" that made the nationalists mad, etc. So, they were fractured, less popular and were ultimately defeated one by one.
How did the Bolsheviks want to change Russia and why did they start the Russian Revolution?
Communist Manifesto nicely summarize their goals. Basically, Bolsheviks saw the chance to overthrow Russian government. Russia continue to persue a fruitless and costly offensive against Central Power (mainly German Empire), and the Russian economy was declining to the point where cost of goods are skyrocketing. More poor class in Russia were attracted by promise of land (Redistirbution of land), peace (End of Russian involvement in WWI) and bread (Sharing all goods, including food, more fairly according to Commmunist idealism). Russians were desparate for improvement, and they supported them.
How did the Bolsheviks manage to take control of Moscow and Petrograd soviets from the Mensheviks during the Russian Revolution?
By having clearly defined program (see The Tasks of the Proletariat in the Present Revolution), while their opponents resorted to slogans and babble.By addressing in aforementioned program the most troubling problems Russia had at the time: peace (cease of WWI) and land ownership.By sloppy actions of both previous content of Soviets (Mensheviks, Social-Revolutionaries and Anarchists) and Provisional Government. The latter failed to pull successful advance in June, the former tried to start uprising in July but failed too.)