We generally find included among the writings of Lactantius a book divided into fifty-two chapters, entitled De Mortibus Persecutorum,
containing an outline of the career of those emperors who displayed active hostility towards the church, an account of the death of each, together with a sketch of the different persecutions from Nero to Diocletian.
The object of the narrative is to point out that the signal vengeance of God in every case overtook the enemies of the faith, and to deduce from this circumstance, from the preservation of the new religion amidst all the dangers by which it was surrounded, and all the attacks by which it was assailed, and from its final triumph over its foes, an irresistible argument in favour of its heavenly origin.
The work appears from internal evidence to have been composed after the victory of Constantine over Maxentius, and before his quarrel with Licinius, that is to say, between A. D. 312 and 315.
The text is corrupt and mutilated, and the statements which it contains must be received with a certain degree of caution in consequence of the declamatory tone in which they are delivered, and the high colouring and trimming employed throughout to suit the particular design proposed.
But notwithstanding these drawbacks, the treatise is extremely valuable on account of the light which it sheds on many obscure passages of ecclesiastical and civil history, and is peculiarly famous as containing a contemporary record of the alleged vision of Constantine before the battle of the Milvian bridge, in consequence of which he ordered the soldiers to engrave upon their shields the well-known monogram representing the cross together with the initial letters of the name of Christ (100.44).
This piece is altogether wanting in the earlier editions of Lactantius, and was first brought to light by Stephen Baluze, who printed it at Paris in his Miscellanea (vol. ii., 1679）
from a very ancient MS. in the Bibliotheca Colbertina, bearing simply the inscription Lucii Cecilii incipit Liber ad Donatum confessorem de mortibus persecutorum.
Baluze entertained no doubt that he had discovered the tract of Lactantius quoted by Hieronymus as De Persecutione Librum Unum,
an opinion corroborated by the name prefixed [LACTANTIUS], by the date, by the dedication to Donatus, apparently the same person with the Donatus addressed in the discourse De Ira Dei,
and by the general resemblance in style and expression, a series of considerations no one of which would be in itself conclusive, but which when combined form a strong chain of circumstantial evidence.
Le Nourry, however, sought to prove that the production in question must be assigned to some unknown L. Caecilius altogether different from Lactantius, and published it at Paris in 1710 as " Lucii Cecilii Liber ad Donatum Confessorem de Mortibus Persecutorum hactenus Lucio Caecilio Firmiano Lactantio adscriptus, ad Colbertinum codicem denuo emendatus," to which is prefixed an elaborate dissertation. His ideas have been adopted to a certain extent by Pfaff, Walch, Le Clerc, Lardner, and Gibbon, and controverted by Heumann and others. Although the question cannot be considered as settled, and indeed does not admit of being absolutely determined, the best modern critics seem upon the whole disposed to acquiesce in the original hypothesis of Baluze.
The most complete edition of the De Mortibus Persecutorum in a separate form, is that published at Utrecht in 1693, under the inspection of Bauldri, with a very copious collection of notes, forming one of the series of Variorum Classics in 8vo.
Other editions are enumerated in the account given of the works of LACTANTIUS.