Abu Bakr

Abu Bakr launched military campaigns against Arabian tribes that renounced Islam or refused to pay zakat after Muhammad's death. The wars, led by generals like Khalid ibn al-Walid, reestablished Muslim control over Arabia and consolidated the caliphate.

After the death of Muhammad, Abu Bakr was elected as the first caliph (successor) at Saqifah. His election unified the Muslim community, though it caused controversy among some supporters of Ali. He became the leader of the nascent Islamic state.

Abu Bakr ordered the compilation of the Quran into a single written manuscript after many memorizers died in the Ridda Wars. Zayd ibn Thabit collected verses from various sources, creating the first official codex, which later served as the basis for Uthman's standard text.

Abu Bakr died after a brief illness, having designated Umar as his successor. His caliphate lasted only two years but established the foundations of the Islamic state, including the expansion beyond Arabia and the preservation of the Quran.