A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Historical events, cultural terms, and designations of time
Names, special terms, and titles of works
Part III. Style 20 spelling

The names of many historical periods and events are traditionally capitalized; more generic terms usually are not, unless they include names. Follow the conventions of your discipline.

the Bronze Age

ancient Rome

the Depression

the nineteenth century

the Industrial Revolution

the Shang dynasty

Prohibition

the colonial period

the Seven Years' War

the baby boom

Nouns and adjectives designating cultural styles, movements, and schools are generally capitalized only when derived from names or when they need to be distinguished from generic terms (as in Stoicism). Again, follow the conventions of your discipline.

classical

Aristotelian reasoning

impressionism

Dadaism

modernism

Hudson River school

deconstruction

Romanesque architecture

Names of days of the week, months, and holidays are capitalized, but names of seasons are not. For more on date systems, see 23.3.

Tuesday

September

Independence Day

spring