The Federal Reserve caused the great depression by pumping unbacked dollars into the economy, destroying price signals for capital allocators and manufacturing an economic boom built on speculation, not real demand.
Then, after the shit hit the fan, more and more government intervention followed.
As if the depression wasn't great enough...
US Congress passed Smoot-Hawley in June 1930, jacking average U.S. tariffs to 45 percent. Sixty countries retaliated immediately. Canada hit American goods. Britain abandoned free trade for the first time in nearly a century, passing the Import Duties Act in 1932. Germany, France, and a dozen smaller nations stacked their own walls on top.
Global trade collapsed 66 percent between 1929 and 1934. A demolition, not merely a slowdown.
Every country's politicians told the same lie: protecting domestic producers would save jobs. What they actually did was destroy the division of labor that made industrial civilization possible. Mises and Hayek had already mapped out the mechanism. Prices coordinate production across borders, signaling where resources flow most productively. Tariffs corrupt those signals and you get misallocated capital, idle factories, and rising unemployment, inside every country that plays the game.
Who the culprit was, is blatantly obvious: nationalist politicians who decided they could manage prosperity by punishing foreign competition. They couldn't. World trade in manufactured goods shrank from $2.9 billion in 1929 to below $1 billion by 1933, measured in constant dollars.
Every retaliating government believed it acted defensively. Every one of them added another layer to the catastrophe. The mechanism requires no conspiracy, only legislators answering to producers instead of consumers, everywhere, simultaneously.