What to read after Lost Legion Rediscovered?

In AD383, according to Bishop Eucherius of Lyon, flooding caused part of the bank of the River Rhone to collapse, revealing a massed grave of thousands of bodies. Eucherius identified these as a legion recruited for the Roman army from the Christians of the Theban district in Egypt, whom he claimed had been massacred nearly a century previously (near the modern village of St Maurice-en-Valais in southwestern Switzerland) for refusing to obey orders they considered immoral. This incident, asserted by Eucherius as matter of fact, is unrecorded elsewhere. Even the existence of this Theban legion is unclear.