Time Line 303
- Diocletian begins a persecution of Christians
- death of Saint Felix of Thibiuca
- death of Saint Procopius
- martyrdom of Saint Anthimus of Rome
- martyrdom of Saint Aaron of Caerleon
- martyrdom of Saint Agathopus
- martyrdom of Saint Acacius
- martyrdom of Saint Adaucus
- martyrdom of Saint Aceolus of Amiens
- martyrdom of Saint Acius of Amiens
- martyrdom of Saint Agapius of Caesarea
- martyrdom of Saint Alexander of Caesarea
- martyrdom of Saint Devota
- martyrdom of Saint Dionysius of Caesarea
- martyrdom of Saint Exuperantius
- martyrdom of Saint Emidius
- martyrdom of Saint Ephysius of Sardinia
- martyrdom of Saint Glycerius of Nicomedia
- martyrdom of Saint Gorgonius
- martyrdom of Saint Heradius
- martyrdom of Saint John of Nicomedia
- martyrdom of Saint Justus of Trieste
- martyrdom of Saint Migdonius
- martyrdom of Saint Mardonius
- martyrdom of Saint Marcellus
- martyrdom of Saint Olympiades
- martyrdom of Saint Pancharius of Nicomedia
- martyrdom of Saint Philoterus
- martyrdom of Saint Pausis of Caesarea
- martyrdom of Saint Romulus of Caesarea
- martyrdom of Saint Saturninus
- martyrdom of Saint Serenus the Gardener
- martyrdom of Saint Sabinus
- martyrdom of Saint Timolaus of Caesarea
- martyrdom of Saint Theodulus
- martyrdom of Saint Victor Maurus
- martyrdom of Saint Venustian
- martyrdom of Saint Zeno of Nicomedia
- martyrdom of the Martyrs of Nicomedia
- martyrdom of the Martyrs of Egypt
- first official Roman edict for the persecution of Christians was issued by Roman Emperor Galerius Valerius Maximianus
| 302 | 304 |
