He was first acquainted with Lenin through the political newspaper Iskra (‘The Spark’) when in London around 1902.
Although originally identifying himself with the Menshevik party, he was formally admitted to the Bolshevik party in August 1917, while still in jail (following a ‘crackdown’ on Bolshevik leadership and revolutionaries by the Provisional Government). Following the November revolution in which he had played a significant role in the organisation and commanding of the military support for the Bolsheviks, Trotsky continued to command the army when Kerensky (ex-prime minister of the Provisional Government) threatened to take back Petrograd with an entourage of loyal soldiers on November 13th. As foreign minister, Trotsky saw the importance of establishing peace, and so took steps towards this in order to fulfil the Bolshevik promise (‘Bread, Peace, Land’). However, his stance on the matter oscillated during the process, as he did not agree to the German’s harsh terms. In the end, it was Lenin who finalised the Treaty of Brest-Litovsk, and Trotsky resigned as foreign minister following this.
Immediately being made commissar of war, he faced the formidable task of turning the military support for the Bolsheviks into a superior ‘Red Army’, which would protect the Bolshevik government against adversaries, both foreign and home-grown, in the inevitable civil war that was becoming more of a reality as time progressed.
Following the success of the Red Army during the civil war, which led to the defeat of the ‘Whites’, and dispelling criticisms from other Bolsheviks of his utilisation of 50,000 former Tsarist officers, Trotsky proved that he was an indispensable attribute to the Bolshevik party and adopted a more prominent role within it. He was seen as Lenin’s ‘right-hand’ man (although considered by some historical references to have been on a par, if not superior to Lenin in many ways), and was one of the initial five members of the Politburo.