Book 4 — Chapter 1 - Rulers of Rome and Alexandria under Trajan
Book IV moves through Trajan, Hadrian, Antoninus, and Marcus Aurelius, including the Bar Kokhba war, early apologists, Polykarpos, Justin, Hegesippus, Melito, Tatian, and Bardaisan. He synchronizes local leadership with imperial reigns, using successions at Rome, Alexandria, Antioch, and Yerushalayim as chronological anchors. These notices are institutional claims from his sources, not proof that every later title or jurisdiction existed in identical form from the beginning. In this reconstruction the chapter coordinate is preserved as Book 4, Chapter 1, and the full subject is retained under the heading 'Rulers of Rome and Alexandria under Trajan'. Names, dates, quoted-source relationships, and political or textual function are kept distinct from Eusebius's own interpretive claims.