The correct answer is the increase in the size of their militaries.
The increase in the size of their militaries gave Hitler and Mussolini the advantage of taking over the smaller countries in Western and Eastern Europe.
Military strength and modern weapons gave Italy and Germany the advantage over many smaller countries in the European region. Mussolini and Hitler forme a convenient association in World Awar II. Along with Japan, they formed the Axis Power. Germany and Italy became allies in 1930, but Hitler arrived in power in 1933. When Hitler became the leader of Germany, Mussolini publicly supported the new German Führer.