As his associates recognized that hitler had became unstable, they

... plotted to assassinate him.

This was the famous "July Plot" of 1944, a plot by senior military officials to detonate a bomb that would kill Hitler.  The briefcase bomb exploded, but Hitler himself sustained only minor injuries.  (There were some other persons killed by the blast.)  Those behind the plot believed Hitler was leading the nation to a catastrophic conclusion to the war, and wanted to replace his government in order to work out a manageable treaty with the Allies who fought against Germany.

Hitler's response was more of his unstable and maniacal approach.  He had hundreds of people arrested on suspicion of conspiracy with the plot, and about 200 were tried and executed.  Some of these executions by slow strangulation with piano wire were filmed for Hitler to be able to watch.

"Operation Valkyrie" was a name given to part of the plans against Hitler, and that name has become associated with the assassination plot overall.  A film dramatization, called Valkyrie, was made about this in 2008.

The effects of the Great Depression and economic collapse led to the acceptance of fascism. Fascism seeks to solve economic challenges by placing the authority in a single person which leads to dictatorship. The main issues that brought forth dictators after World War I were economic--The Great Depression stuck Europe almost as hard as it struck the US, and people were desperate for options and strong leadership. This is the recipe for authoritarianism. thats not ten sentences but it will help