Dr. Franklin identifies him as David McIntyre, a former Earthforce gunnery sergeant. McIntyre was the soldier who fired the very first shots at the Minbari cruiser Valen'Tha (the event that started the Earth-Minbari War). He has suffered from severe PTSD ever since, replacing his traumatic reality with the Arthurian persona.
How this episode the final, peaceful state of the Narn? [S3E13] A Late Delivery from Avalon
An enigmatic man (Michael York) arrives on Babylon 5 in medieval armor, convinced he is the reincarnation of King Arthur Pendragon, sent by the Vorlons to combat a new darkness. not just ignoring them.
The episode deals with the heavy weight of being "just following orders," emphasizing that true healing requires coming to terms with one's actions, not just ignoring them. [S3E13] A Late Delivery from Avalon