Does the nationalism always unify people? explain in detail.

No

Explanation:

Nationalism is a concept that came to life in the 19th Century with the birth of the first modern nation state. During the World Wars, nationalism played an important part in the role of the aggressor nations and also of the nations that were attacked.

After the war, however, it became increasingly clear that nationalistic tendencies were not necessarily a unifying factor, and could actually split nations apart. Differences arise when not all citizens of the country agree on what defines their country as a nation.