Battle of Callinicum

The Battle of Callinicum took place Easter day, 19 April 531, between the armies of the Eastern Roman Empire under Belisarius and the Sassanid Persians under Azarethes. After a defeat at the Battle of Dara, the Sassanids moved to invade Syria in an attempt to turn the tide of the war. Belisarius' rapid response foiled the plan, and his troops pushed the Persians out of Syria through skillful maneuvering before forcing a battle.

Battle
In April 531, a Persian force under Azarethes, numbering about 15,000 cavalry, with an additional group of 5,000 Lakhmid Arabs, crossed the frontier at Circesium on the Euphrates and marched north. As they neared Callinicum, Belisarius, who commanded the local Byzantine troops, set out to follow them as they advanced westwards. Belisarius' forces consisted of about 5,000 men and another 3,000 Ghassanid Arab allies, for the remainder of his army had been left to secure Dara. The Byzantines finally blocked the Persian advance at Chalcis, where reinforcements under Hermogenes also arrived, bringing the Byzantine force to some 20,000 men. The Persians were forced to withdraw, and the Byzantines followed them east.

Initially, Belisarius only wanted to drive off the Persians, without a risky battle. The Byzantine troops, however, were restless, and clamored for battle. After failing to convince his men, and realizing they would mutiny unless he agreed, Belisarius prepared his force for battle.

The two armies met outside Callinicum on 19 April 531. Both groups formed up differently, Belisarius again choosing an "odd" formation that confused his opposing general. In this case he anchored his left flank on the bank of the river with infantry, put the Ghassanid Arab allies on the right flank, and placed several ranks of heavy cavalry, the cataphracts, in the center of the front line. In more standard formation the Persians split their forces into two roughly equal groups, with infantry in front of cavalry.

For much of the day, the battle was a stalemate, with the Persians and Byzantines trading arrows and cavalry charges. After "two thirds of the day" had elapsed a squadron of the elite Persian cavalry broke through the Roman right flank, composed of Belisarius' Ghassanid allies, with surprising force such that the Ghassanids were accused of treachery after they fled. With his right flank gone, Belisarius was forced to retreat in an effort to re-form his line, but the retreat was followed and soon the Romans found themselves pressed against the river.

Zacharias of Mytilene says of this battle:

"[The Romans] turned and fled before the Persian attack. Many fell into the Euphrates and were drowned, and others were killed."

However, it is unknown what stage of the battle Zachariah was referring to.

Here on the river, the Romans were able to resist the Persians and withdraw much of their army across the river. The Persians attacked the Byzantine lines over the course of several hours, killed many resisting Roman troops, and inflicted heavy casualties on them. Eventually, the Romans gave up, and Belisarius fled with his soldiers.

Outcome
The direct outcome of the battle was something of a stalemate; the Byzantine army had lost many soldiers and would not be in fighting condition for months, but the Persians had taken such heavy losses that it was useless as to its original purpose, the invasion of Syria.

Upon return, Emperor Kavadh I removed General Azarethes from command and stripped him of his honors due to the general's actions in the battle.

This mutual disaster was the first of Belisarius' series of (relatively) unsuccessful wars against Sassanids, which led Byzantine to pay heavy tributes in exchange for a peace treaty and the remaining Byzantine land still in Persian hands.

Callinicum ended the first of Belisarius' Persian campaigns, returning all of the land lost to them to Roman rule under Justinian I in the Eternal Peace agreement signed in summer 532.