Nationalism after Unification

What made the Axis powers so much more nationalist than others? Japan, Italy and Germany have in common that before the 20th century they had only recently become unified: nationalism may have been an antithesis to an earlier period of fragmentation. Once progressing in that direction began to solve any problems at all, it was easy to think that continuing to do so would lead to the solution of all problems. Relatively recent unification can lead to a lasting euphoria of nationalism.