European nations believed in order to be a great nation one must have a strong army.
Step-by-step explanation:
European nations pre world war one were at the heights of their economic powers and their inter competition vying for power imperial and at home upfront was a massive strain on the world at that time.
All major powers were swelling up their military to a brink and making sure that they would have the upper hand in case of a conflict which was not the way to go as the powers became increasingly paranoid of one another.