Sixth Syrian War
The Sixth Syrian War (170–168 BCE) was the final conflict of the Syrian Wars between the Ptolemaic Kingdom and the Seleucid Empire that last between 170 BCE and 168 BCE. The war would begin when Eulaeus and Lenaeus who were both regents of the young Ptolemy VI Philometer of the Ptolemaic Dynasty of Egypt declared war on Antiochus IV Epiphanes. The same year the two young siblings of Ptolemy VI named Ptolemy VIII Euergetes II and Cleopatra II were declared co-rulers to help bolster the security of the Ptolemaic Kingdom.
However, it was not meant to last. The military campaign began in 169 BCE and soon Antiochus VI gained the advantage when he captured Pelusium. At this point the Egyptians replaced Eulaeus and Lenaeus with two new regents named Comanus and Cineas who were commissioned to negotiate peace with the Seleucids. From here Antiochus would take Ptolemy VI Philometer who was his nephew into his guardianship which gave him control over Egypt. However, this was not what the population of Alexandria had in mind.
The people of Alexandria would declare Ptolemy XIII Physcon the official king of the Ptolemaic Kingdom and at this point Antiochus began a siege of the city. He was never able to cut off communication and supply lines however, so by 169 BCE he withdrew. After Antiochus retreated Ptolemy VI and his brother would reconcile. However, this would only further agitate Antiochus IV Epiphanes who wanted direct control over the king.
This would force the Egyptians to request military aid from the Roman Republic. The senate would dispatch Gaius Popilius Laenas to Alexandria to help reinforce and fortify the Ptolemaic Kingdom. It was necessary for the Romans to maintain their supply of grain from Egypt which allowed them to sustain a massive growing population. During the same time Antiochus would seize the island of Cyprus and then Memphis and would begin to march on Alexandria next. While at Eleusis which was on the outskirts of Alexandria he would meet Popilius Laenas whom he knew personally from his stay at Rome.
Expecting a friendly interaction instead the Roman gave him an ultimatum from the Roman senate. The Romans wanted the Seleucids to retreat from Egypt and Cyprus at once or risk being attacked. Antiochus asked the Roman for time to consider to which apparently he drew a circle around him in the sand and told him to decide before he stepped outside. Not wanting to risk confrontation with the Romans the Seleucids backed down and the "Day of Eleusis" became known as the day the final Sixth Syrian War ended. With the end of the Syrian Wars came the end to the Seleucid dream of capturing the Ptolemaic Kingdom.