What were the causes and consequences of the crisis of the 1929 and the emergence of the fordist-keynesian era?

The crisis of 1929 marked the end of an era and the emergence of the fordist-keynesian era, in which the participation of the State was key.
The crisis of 1929 was caused by economic factors, as well as the consequences of the peace signed after World War I and the reparations imposed by the victorious powers.
The New Deal policy was a response to the crisis, with unprecedented public works, subsidies for companies, minimum wage, popular housing, among others.
John Maynard Keynes was an economist who abandoned the neoclassical approach and proposed a theory that placed the State at the center of the strategy to combat the crisis.