Final answer:
In the 1930s, Germany began expanding aggressively by rebuilding the German military.
Step-by-step explanation:
In the 1930s, Germany first began to expand aggressively by rebuilding the German military. This was a key aspect of Nazi Germany's plan to assert its power and dominance in Europe. By increasing its military strength, Germany aimed to intimidate and conquer other nations.
Learn more about Germany's aggression and military expansion in the 1930s