The Indian Rebellion and the Raj
Indian soldiers of the East India Company's army revolted — the spark was a rumor that new cartridges were greased with cow and pig fat, offensive to Hindus and Muslims alike — and the uprising spread into a widespread revolt against Company rule. Both sides committed atrocities; the Company won, and was then abolished. The British Crown took direct control of India, ending the strange era in which a corporation had governed a subcontinent, and beginning ninety years of formal empire.
Hardship plus a sudden opening (weak state, lost war, fiscal collapse) lets those who bear it overthrow the order — usually installing a new elite.