The causes of the Sixth Syrian War…

The causes of the Sixth Syrian War are obscure.

Eulaeus and Lenaeus, the two regents of the young king of Egypt, Ptolemy VI Philometor, declare war on the Seleucid ruler Antiochus IV Epiphanes in 170.

Ptolemy's younger siblings Ptolemy VIII Physcon and Cleopatra II are in the same year declared co-rulers in order to bolster the unity of Egypt.

Military operations do not begin until 169, when Antiochus quickly gains the upper hand, seizing the important strategic town of Pelusium.

The Egyptians realize their folly in starting the war, Eulaeus and Lenaeus are overthrown and replaced by two new regents, Comanus and Cineas, and envoys are sent to negotiate a peace treaty with Antiochus.

Antiochus takes Ptolemy VI (who is his nephew) under his guardianship, giving him effective control of Egypt.

However, this is unacceptable to the people of Alexandria, who respond by proclaiming Ptolemy Physcon as sole king.

Antiochus besieges Alexandria but he is unable to cut communications to the city so, at the end of 169, he withdraws his army.

In his absence, Ptolemy VI and his brother are reconciled.

Antiochus, angered at his loss of control over the king, invades again.

The Egyptians send to Rome asking for help and the Senate dispatches Gaius Popilius Laenas to Alexandria.

Meanwhile, Antiochus has seized Cyprus and Memphis and is marching on Alexandria.

At Eleusis, on the outskirts of the capital, he meets Popilius Laenas, with whom he had been friends during his stay in Rom, but instead of a friendly welcome, Popilius offers the king an ultimatum from the Senate: he must evacuate Egypt and Cyprus immediately.

Antiochus begs to have time to consider but Popilius draws a circle round him in the sand with his cane and tells him to decide before he steps outside it.

Antiochus chooses to obey the Roman ultimatum.

The "Day of Eleusis" ends the Sixth Syrian War and Antiochus' hopes of conquering Egyptian territory.