How did the government leaders in Egypt and Tunisia lose their positions?

Three years after the beginning of the Arab uprisings, Tunisia and Egypt are moving in different directions. Tunisia has achieved considerable success in adopting a constitution through a process that, despite delays, interruptions, and other crises, has remained reasonably democratic. While still a long way from being a consolidated democracy, the country may yet become one without further upheavals. Not so in Egypt, which has reverted to an authoritarian and repressive regime, more openly militaristic than any since Gamal Abdel Nasser's days; as a result, a new process of democratization is unlikely to start without other uprisings.