One of the reasons World war one started was Militarism, militarism used to be known as an “arms race.” Because Britain expanded their navy, Germany wanted to do the same These countries competed to build the biggest and strongest army. For reasons of protection and power, the more a nation continued to build up their navy and army, the more other countries felt pressured to do the same. The cost of the " arms race " fell on the civilian population in the form of high taxes, all the major powers except Great Britain and the United States, doubled the size of their armies.
The nations of Europe had been creating alliances for over 20 years.