After Jovian had reigned about eight months, he died suddenly at Dadastana, a town of Bithynia, while on his road to Constantinople.
Christianity · Church History · Ecclesiastical History
Book VI, Ch. 6 — Death of Jovian; The Life of Valentinian, and his Confidence in God; how he was advanced to the Throne and selected his Brother Valens to reign with him; the Differences of Both.
Ecclesiastical History · Salminius Hermias Sozomen