The leaders of these countries mainly tried a two-pronged strategy. They tried to build their militaries and to take over some amount of empire.
Germany and Japan, in particular, tried to increase the power of their militaries. Germany had to rebuild after not being allowed much of a military after WWI. Japan had not been deprived of a military, but it had also not been a first rate power. Therefore, it pushed to increase the power of its military as well.
All three countries were eager to expand their territory in the time before WWII. Germany annexed Austria and, eventually, all of Czechoslovakia. Italy tried to take an empire in Africa. Japan built up its possessions in Micronesia and Manchuria and then looked to take more of China.
In these ways, all of these countries tried to become major powers in the 1930s.
The leaders of Germany, Japan, and Italy used similar strategies to transform their countries into strong world powers before World War II began.
One strategy they used was to develop a strong sense of nationalism. The leaders in each of these countries felt their country had been wronged by events after World War I. The Germans resented having to pay $33 billion in reparations. They resented having to accept responsibility for World War I. Hitler told the German people they should get revenge for this mistreatment caused by the terms of the Versailles Treaty. He indicated that countries couldn’t mistreat Germany without expecting some form of retaliation to occur. By taking these positions, he began to build up the German spirit of nationalism.
Mussolini did the same thing in Italy. He felt Italy should have received more land than it did from the Versailles Treaty. He vowed to restore Italian pride to the levels that existed during the days of the Roman Empire. He felt Italy needed to get revenge for the mistreatment that resulted from the terms of the Versailles Treaty.
The Japanese believed they were mistreated by the terms of the Five Power Naval Treaty developed at the Washington Conference in 1921. They resented that they were allowed to have fewer warships than Great Britain and the United States. They felt Japan should have been treated as an equal to the United States and to Great Britain.
Another strategy the leaders in these countries used was to build up their military. The leaders in these countries knew they were going to have to invade other places to get resources and to get land. Building up the military would not only provide the military power needed to carry out these invasions, it would put people back to work and would help their economies recover from the effects of the Great Depression.
The leaders of Germany, Japan, and Italy used similar strategies to build their countries into strong nations before World War II began.