The Youngest of Cleopatra and Mark Antony's Three Children Disappeared From the Historical Record at Age Four

Ptolemy Philadelphus was born at Alexandria in late 36 BC, the third of the three children of Cleopatra VII and Mark Antony. His older brother Alexander Helios and his twin sister Cleopatra Selene II had been born in 40 BC; Ptolemy was their younger sibling by approximately four years. The regnal name was chosen to evoke the second Ptolemy of the dynasty (Ptolemy II Philadelphus, reigned 283–246 BC, the substantial patron of the Library of Alexandria) and substantively to position the infant as a future Ptolemaic king.

The substantial Donations of Alexandria of November 34 BC — Antony’s public-political ceremony that distributed the eastern Mediterranean provinces among Cleopatra’s children — gave the two-year-old Ptolemy the titular kingdoms of Syria, Phoenicia, and Cilicia. The ceremony was substantively the proximate political cause of the Octavian-Antony breach that produced the subsequent Actium campaign of 31 BC.

Antony killed himself at Alexandria on 1 August 30 BC after the Actium defeat. Cleopatra followed approximately ten days later. Octavian took the three Antony-Cleopatra children — Alexander Helios (10), Cleopatra Selene (10), and Ptolemy Philadelphus (4) — to Rome under the custody of Antony’s Roman wife Octavia Minor (Octavian’s sister, substantively the woman Antony had abandoned for Cleopatra in 37 BC).

The three children were paraded as captives in Octavian’s triple triumph of August 29 BC. The subsequent surviving Roman historical record (Plutarch, Cassius Dio, Suetonius) substantively follows the older two: Cleopatra Selene was married to King Juba II of Mauretania in approximately 25 BC and substantively lived as a queen there until approximately 5 BC; Alexander Helios disappears from the record after approximately 25 BC but was substantively probably accompanying his sister to Mauretania.

Ptolemy Philadelphus disappears earlier. The last surviving documentary reference is the triumph of 29 BC. He is substantively presumed to have died young, probably between approximately 29 and 26 BC, in the Octavia household at Rome. The cause is substantively undocumented. He was four years old at the last surviving reference and substantively probably did not live past eight or nine.

His siblings substantively founded subsequent royal lineages. He substantively did not. The younger son of Cleopatra and Antony substantively left no descendants and substantively no archaeological or documentary trace beyond the single Roman-triumph reference of 29 BC.