What topic did authors of the 1850s become deeply interested in?

https://www.britannica.com/list/periods-of-american-literature

Explanation:

The history of American literature stretches across more than 400 years. It can be divided into five major periods.

The Colonial and Early National Period (17th century to 1830)

The Federalist Papers (1787–88)

The Romantic Period (1830 to 1870)

Realism and Naturalism (1870 to 1910)

The Contemporary Period (1945 to present)

the style of music that was composed during the classical era was concerto grosso.