When did nationalism become more extreme?

The political development of nationalism and the push for popular sovereignty culminated with the ethnic/national revolutions of Europe. During the 19th century nationalism became one of the most significant political and social forces in history; it is typically listed among the top causes of World War I.

Explanation:

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.

yes they have. but is this a true false question? if it is, the answer is true.