Antigonus I Monophthalmus

Antigonus I Monophthalmus (“the One‑Eyed”) was one of the most powerful of the Diadochi, the successors of Alexander the Great. Born c. 382 B.C., he rose from a Macedonian general to become the self‑proclaimed King of Asia and nearly succeeded in reuniting Alexander’s empire under his own rule. His death at the Battle of Ipsus in 301 B.C. ended the last serious attempt to restore the unified Macedonian dominion.

Early Life and Service Under Alexander

Antigonus was born in Macedon and served as a distinguished officer under Philip II of Macedon and later under Alexander the Great. During Alexander’s campaigns, Antigonus commanded forces in Asia Minor and was appointed satrap of Phrygia after the conquest of Persia.

His military skill, administrative ability, and loyalty made him one of Alexander’s most trusted commanders.

Role After Alexander’s Death

Following Alexander’s death in 323 B.C., Antigonus became one of the leading figures in the turbulent struggles among the Diadochi. Initially confirmed as satrap of Phrygia, he soon clashed with other successors, including Perdiccas, Eumenes, and Cassander.

Antigonus defeated Eumenes in 316 B.C., gaining control over much of Asia Minor and the eastern provinces. His growing power alarmed the other Diadochi, who formed coalitions to oppose him.

Rise to Kingship

In 306 B.C., after a major naval victory at the Battle of Salamis (Cyprus), Antigonus and his son Demetrius I Poliorcetes declared themselves kings. Antigonus adopted the royal title:

Basileus and King of Asia

This act prompted the other Diadochi—Ptolemy I Soter, Seleucus I Nicator, Lysimachus, and Cassander—to assume royal titles as well, marking the final break from the unity of Alexander’s empire.

Conflict with the Diadochi

Antigonus sought to reunite Alexander’s empire under his rule. His campaigns extended across:

Syria
Mesopotamia
Asia Minor
Greece (through Demetrius)

His ambitions brought him into direct conflict with Seleucus and Lysimachus, who feared his growing dominance.

Battle of Ipsus (301 B.C.)

The decisive confrontation occurred at the Battle of Ipsus in Phrygia. Antigonus and Demetrius faced the combined armies of Seleucus and Lysimachus.

Key factors in the battle included:

Seleucus’ deployment of war elephants
Superior coalition numbers
Demetrius’ cavalry being cut off from Antigonus’ main line

Antigonus, then nearly 80 years old, was struck down by enemy missiles during the fighting. His death ended the last major attempt to reunify Alexander’s empire.

Legacy

Antigonus I Monophthalmus is remembered as:

One of the most capable and ambitious of the Diadochi
Founder of the Antigonid dynasty
Father of Demetrius I Poliorcetes
Grandfather of Antigonus II Gonatas

Although he failed to restore Alexander’s empire, his descendants ruled Macedon for nearly a century.

Sources

Cambridge Ancient History
Dictionary of Greek and Roman Biography and Mythology

Antigonus I Monophthalmus

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