Since the war was over, there was nothing for Hitler to fight against or fight for, since France, Britain and the USA had all burdened Germany with the terms of the Treaty, and he believed his country was betrayed from the home front. He was hired as an intelligence officer to infiltrate the German Workers Party.
At one of the party meetings, the Party Chairman, Anton Drexler, noticed Hitler’s charisma when speaking so gave him a pamphlet named “My Political Awakening”. This pamphlet contained much antisemitic, nationalist, anti-communist and anti-capitalist material, which could’ve possibly embedded themselves in Hitler’s brain.
After fully joining the party in 1920, he renamed it to the National Socialist German Worker’s Party, or Nazi for short, and redesigned the logo to be a black swastika, a symbol commonly found in Hinduism meaning spirituality and divinity and a pattern which you can find around the world including buildings in London, with a white circle and red background.
In June 1921, there was a mutiny in the party, which kicked out Drexler and Hitler became the party chairman, where he spoke at beer halls, a type of large German pub. Early followers included Hermann Goering, a former flying ace, Ernst Rohm, a WW1 veteran and was later found out to be homosexual, and Rudolf Hess, another WW1 veteran and met Hitler at one of his speeches in 1920. Rohm later became the head of the Nazi’s Paramilitary force, the Stormtroopers or SA.