Explain the process of nation building that occurred in the nineteenth century. What polities initiated these efforts, and what different strategies were involved?

Generally, nation-building (or nation formation) is defined as the process of creating a nation and establishing the national identity with the help of the government and the state. However, it is also a concept that can mean the helping of underdeveloped and weak centuries and/or economies in order to make them more stable. It means state-building, modernization, socio-economic and political development, and reconstruction.
The second half of the nineteenth century was an age of nationalism, or nation-building. Many countries, especially European countries, took an initiative to build their nations and establish their national identity. The majority of the European countries were countries of different cultures and languages. In order to strengthen their nations and provide bigger security, the rulers, the elites, and those who governed these countries decided to form their national identities and incorporated various strategies and policies in acquiring this goal and building the community and the society.
Thus, during the 19th century, the rulers of France, Italy, Russia, England, and Germany established their national identities and banned any other languages other than the “national language” in every area of society: education, religion, and administration; they developed the countries’ infrastructure and extended road and rail links; they made sure that the military is compulsory for all young men and will have soldiers from all regions of their countries; they used education to promote nationalism and made primary education compulsory for all children; and they began calling their citizens “French, Italian, Russian, English, and German citizens.”
Thus, the most common strategy used by the elites in nation-building was the process of homogenization, mainly because its effects were durable: the language(s) learned will not be forgotten; the roads built will remain in the future; the preferences of the governments will remain relevant and influential in the future as well.
Similarly to the European countries, America also formed its nation, its national identity, and national language, however, the concept of nation-building in the U.S. is better defined as state-building, in which the US national government “built state capacity to enforce its authority over expansive territory and the populations inhabiting it.” The formation of the Republican Party in the 1850s, and the Declaration of Independence were a powerful nationalist symbol for the diverse American nation. The Union forces won the Civil War and the Fourteenth Amendment was passed to the Constitution, thus the American citizenship was defined for the first time.
While nation-building in the 19th century was most prominent in Europe and the U.S., in the modern era nation-building is mainly characteristic for some of the African countries and the Balkans.