Hosni Mubarak, the former Egyptian strongman, has died at 91. His three-decade hold on power was upended during the Arab Spring in 2011.

Mr. Mubarak had once appeared invincible. He had survived multiple assassination attempts, held power longer than anyone since Muhammad Ali Pasha, the founder of the modern Egyptian state, suppressed a wave of terrorism by Islamic fundamentalists and appeared even to defy the gravity of age.