Arsinoë IV (; between 68 and 63 BC – 41 BC) was the fourth of six children and the youngest daughter of Ptolemy XII Auletes. Queen and co-ruler of Ptolemaic Egypt with her brother Ptolemy XIII from 48 BC – 47 BC, she was one of the last members of the Ptolemaic dynasty of ancient Egypt. Arsinoë IV was also the half sister of Cleopatra VII. For her role in conducting the siege of Alexandria (47 BC) against her sister Cleopatra, Arsinoë was taken as a prisoner of war to Rome by the Roman triumvir Julius Caesar following the defeat of Ptolemy XIII in the Battle of the Nile. Arsinoë was then exiled to the Temple of Artemis at Ephesus in Roman Anatolia, but she was executed there by orders of triumvir Mark Antony in 41 BC at the behest of his lover Cleopatra VII. History Arsinoë was the third, possibly fourth daughter of Ptolemy XII by an unknown woman (presumably since Cleopatra VII's probable mother Cleopatra V had died or been repudiated not long after Cleopatra VII was born.) When Ptolemy XII died in 51 BC, he left his eldest son and daughter, Ptolemy and Cleopatra, as joint rulers of Egypt, but Ptolemy soon dethroned Cleopatra and forced her to flee from Alexandria. Julius Caesar arrived in Alexandria in 48 BC pursuing his rival, Pompey, whom he had defeated at the Battle of Pharsalus. When he arrived in Alexandria, he was presented with Pompey's head. The execution of his longterm rival ended the possibility of an alliance between Caesar and Ptolemy, and he sided with Cleopatra's faction. He declared that in accordance with Ptolemy XII's will, Cleopatra and Ptolemy would rule Egypt jointly, and in a similar motion restored Cyprus, which had been annexed by Rome in 58 BC, to Egypt's rule and gave it to Arsinoë and her youngest brother, Ptolemy XIV. However, Arsinoë then escaped from the capital with her mentor, the eunuch Ganymedes, and took command of the Egyptian army. She also proclaimed herself Queen as Arsinoë IV, executed Achillas, and placed Ganymedes second in command of the army immediately below herself. Under Arsinoë's leadership, the Egyptians enjoyed some success against the Romans. The Egyptians trapped Caesar in a section of the city by building walls to close off the streets. Then Arsinoë directed Ganymedes to pour seawater into the canals that supplied Caesar's cisterns which