Abu Bakr vs John I Tzimiskes

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.

John I Tzimiskes became emperor after assassinating his uncle Nikephoros II Phokas. He was a skilled general and continued the military expansion of the Byzantine Empire.

John I led a campaign against the Rus under Sviatoslav I, who had invaded Bulgaria. He defeated the Rus at the Battle of Dorostolon in 971, forcing Sviatoslav to withdraw. This secured Byzantine control over the Balkans.

John I launched a major campaign into Syria, capturing Damascus, Beirut, and other cities. He advanced as far as Jerusalem, but did not capture it. These campaigns extended Byzantine influence in the Levant.

John I Tzimiskes died suddenly, possibly from poison. His death cut short his ambitious campaigns. He was succeeded by Basil II, who would later become known as the 'Bulgar-Slayer'.