Byzantine civil war of 1321–1328

Byzantine Empire and surrounding territory in 1307, shortly before the First Palaiologan Civil War.

Date	1321 to 1328
Location	Thrace, Macedonia and Constantinople
Result	Andronikos III becomes co-emperor and finally sole emperor.

Belligerents

Andronikos II Palaiologos

Serbian Kingdom

Andronikos III Palaiologos

Second Bulgarian Empire

Commanders and leaders

Andronikos II
Syrgiannes Palaiologos

Andronikos III
John Kantakouzenos,
Theodore Synadenos,
Syrgiannes Palaiologos

Strength

Unknown
- Numerous Bulgarian, Serbian, and Tartar mercenaries,
- Smaller number of supporters.
- Population of Constantinople.

Unknown,
- Numerous mercenaries
- Younger nobility
- Included more supporters, including non-combatants,
- Population of Thrace and Macedonia.

Casualties and losses

First conflict (1321): unknown
*Second conflict (1322): few, or light;
*Third conflict (1327–28): possibly heavier, but comparatively light.

Unknown, but also possibly comparatively light

Andronikos II Palaiologos

Andronikos III Palaiologos

The Byzantine civil war of 1321–1328 was a series of conflicts fought in the 1320s between the Byzantine emperor Andronikos II Palaiologos and his grandson Andronikos III Palaiologos over control of the Byzantine Empire.

Following the accidental murder of his brother Manuel over a love affair, the emperor Andronikos II excluded Andronikos III from the succession, while Michael IX, the son of Andronikos II and next in line for succession, died from shock over his son's death.

Andronikos III had many supporters, chief among them John Kantakouzenos and Syrgiannes Palaiologos, who bought themselves governorships in Thrace, where discontent with the old emperor was high. On Easter 1321, Andronikos III fled the capital to Adrianople, where he set up his court and initiated an uprising against his grandfather. Syrgiannes Palaiologos led a large army towards the capital, forcing the old emperor to negotiate. On 6 June 1321 a peace agreement was concluded, whereby Andronikos III was recognized as co-emperor and assigned Thrace and districts in Macedonia, while the rest, including Constantinople, remained under Andronikos II, who, as senior emperor, would also direct the empire's foreign policy.

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