The causes of this conflict are obscure. In 170, Eulaeus and Lenaeus, the two regents of the young king of Egypt Ptolemy VI Philometor, declared war on the Seleucid ruler Antiochus IV Epiphanes. In the same year, Ptolemy's younger siblings Ptolemy VIII Physcon and Cleopatra II were declared co-rulers in order to bolster the unity of Egypt. Military operations did not begin until 169 when Antiochus quickly gained the upper hand, seizing the important strategic town of Pelusium. The Egyptians realised their folly in starting the war, Eulaeus and Lenaeus were overthrown and replaced by two new regents, Comanus and Cineas, and envoys were sent to negotiate a peace treaty with Antiochus. Antiochus took Ptolemy VI (who was his nephew) under his guardianship, giving him effective control of Egypt. However, this was unacceptable to the people of Alexandria who responded by proclaiming Ptolemy Physcon as sole king. Antiochus besieged Alexandria but he was unable to cut communications to the city and he also needed to deal with a revolt in Judaea so, at the end of 169, he withdrew his army. In his absence, Ptolemy VI and his brother were reconciled. Antiochus, angered at his loss of control over the king, invaded again. The Egyptians sent to Rome asking for help and the Senate despatched Gaius Popilius Laenas to Alexandria. Meanwhile, Antiochus had seized Cyprus and Memphis and was marching on Alexandria. At Eleusis, on the outskirts of the capital, he met Popilius Laenas, with whom he had been friends during his stay in Rome. But instead of a friendly welcome, Popilius offered the king an ultimatum from the Senate: he must evacuate Egypt and Cyprus immediately. Antiochus begged to have time to consider but Popilius drew a circle round him in the sand with his cane and told him to decide before he stepped outside it. Antiochus chose to obey the Roman ultimatum. The "Day of Eleusis" ended the Sixth Syrian War and Antiochus' hopes of conquering Egyptian territory.