How are the Revolutions of 1848 important in the book, Age of Anger?

In the year 1848, numerous revolutions broke out across Europe and subsequently failed. Nationalist Italians embarked on a nation-building enterprise, which did not succeed, and many nationalist intellectuals experienced the crushing disappointment of watching their ideals be shattered. Mishra writes of numerous literary and historical examples of men for whom 1848 changed a great deal: it turned even liberal-minded thinkers into cynics.