Final answer:
Hitler violated the Treaty of Versailles by remilitarizing the Rhineland, expanding the military, and producing banned weapons. The allied powers' policy of appeasement led to an underestimation of Hitler's ambition, potentially missing opportunities for deterrence that could have prevented World War II.
Step-by-step explanation:
Adolf Hitler defied the League of Nations and violated the Treaty of Versailles in several significant ways. His actions included withdrawing Germany from the League of Nations, remilitarizing the Rhineland, rebuilding the German military, and producing prohibited offensive weapons like submarines and tanks. Hitler justified these actions as necessary for national defense given European military expansions. However, his moves also paved the way for annexations and aggression that led to World War II.
Regarding hypothetical alternatives to war, one could speculate that if the allied powers had confronted Hitler earlier and more firmly, a stronger deterrent might have been established. The policy of appeasement allowed Hitler to become emboldened, and efforts to enforce the treaty's terms were insufficient. However, given the devastation after World War I, many were reluctant to engage in conflict again, leading to an underestimation of Hitler's ambitions.