Book 5 — Chapter 23 - The Dispute concerning Pesach
Book V centers on the persecution in Lugdunum and Vienna, Irenaeus, the Phrygian prophetic movement, Roman successions, and the major dispute over the date of Pesach. The dispute concerns calendar and inherited practice, especially the Asian observance tied to the fourteenth day and the opposing Roman custom. Eusebius preserves letters from both sides and shows that some leaders resisted excommunication over the disagreement. In this reconstruction the chapter coordinate is preserved as Book 5, Chapter 23, and the full subject is retained under the heading 'The Dispute concerning Pesach'. Names, dates, quoted-source relationships, and political or textual function are kept distinct from Eusebius's own interpretive claims.