How Did Early Christians View Military Service?

I have had in my library for about twenty years now a book (second edition) by Jean-Michel Hornus (translated by Alan Kreider and Oliver Coburn), IT IS NOT LAWFUL FOR ME TO FIGHT. Early Christian Attitudes Towards War, Violence, and the State (Herald Press: Scottdale, PA / Kitchener, Ontario, 1980) 370 pages. It puts into perspective the fact that there were (some--very few) soldiers who found themselves in an especially dangerous position because, now that they had accepted the Gospel, they were finding themselves increasingly conflicted and subject to execution should they follow the dictates of their conscience in refusing to act out entirely the role expected of soldiers in the emperor's service. However, there were other nominal Christians serving as soldiers who had the name of being Christian before ever they found themselves in the emperor's military. Hornus puts all this in perspective:

"But we can say confidently that the Christians then in the army ["a result of Roman recruiting methods of compulsory service whereby a as certain category of persons would be impressed all over the empire at a time when Christianity, as an unrecognized religion, could not provide grounds for exemption"] had not enlisted voluntarily after they had become Christians. Their presence in it, which initially was a result of the persecution, soon ran the risk of eliciting further persecution, as uncompromising Christians began to bring out, for all to see, the latent opposition between their faith and the empire. The more cautious believers [i.e., the ones more fainthearted and willing to make compromise of their faith] were therefore enraged and terrified to hear [, for example,] of the soldier's daring exploit in Tertullian's De Corona [, "which concerns a soldier who suddenly refused to wear a laurel wreath which was given him, in accordance with custom, at the time of donativum. Many Christians were critical of his refusal; but Tertullian defended it by moving progressively from a discussion of the nature and significance of garlands to a clear and categorical denunciation of military service. Two things are especially noteworthy here: until his sudden gesture this Christian had been a soldier; and Tertullian tells us that there were other Christian soldiers who did not have the courage to follow his example."]--pp. 123-24.

Hornus helps us to appreciate that some nominal Christians were in the military and were soldiers before they heard the Gospel. After hearing the Gospel, some became increasingly conflicted until they made open acknowledgment of their newfound faith-- and paid the price for it. Other nominal Christians who were in the military after they had become Christians were in the military because they were impressed under persecution so that they compromised their faith when becoming soldiers for the emperor. Some of these later found courage of their convictions--and they, too, paid the price for it. Many others remained cowered by Roman persecution.

Clement addresses a situation where some soldiers become believers. Hornus helps us to appreciate the real meaning of what Clement advised. Hornus quotes Clement, and afterwards makes comments on Clement's words. (I have added in brackets words that are not a quotation taken from Hornus' book, but are words that present the meaning that Hornus argues was in Clement's words.)  So, in Hornus' book we read:

                         ""Till the ground, we say, if you are a husbandman,
                            but recognize God in your husbandry. Sail the
                            sea, you who are seafaring; but ever call on the
                            heavenly pilot. Were you a soldier on campaign
                            when the knowledge of God laid hold on you? 
                            Then listen [as any good soldier would listen
                            to his commander, but only now you should be
                            determined to listen instead to the only
                            worthwhile commander,] to the commander
                            who signals righteousness.... "

"This text is not to be interpreted as an approbation of [Roman] military service; rather it must almost certainly be understood as an invitation to leave the army.... From these various passages [where Clement touches on soldiering] we may conclude that military life was a reality which Clement observed in the world; but it was not a course of action which he endorsed for the Christian."--pp. 124-25

I find Hornus especially insightful in what he writes on page 67:
"Once one admitted that Constantine was God's elect, one was compelled to falsify the historical truth where necessary to make his personality correspond to [traditional Christian] expectations [of how a spiritual brother ought to treat another brother] . . . Thus, while Constantine and Licinius were still fighting as allies against Maxentius and Daia, the first editions of Eusebius and Lactantius depicted both men--Licinius as well as Constantine--as acting in God's name and with his help. But later, after Constantine had
quarreled with Licinius and then deposed him, the two Christian writers had to make hurried and clumsy emendations in their work.
Now they vilified Licinius and attempted to demonstrate retrospectively that in reality the light of God's grace had all along shown on Constantine alone. The most egregious Soviet historians of the Stalinist period could scarcely have done better--or worse."

I may post more excerpts from Hornus. But I recommend that you visit a library in order to read all of Hornus' work. He helps put the lie to some revisionist historiography, namely, that which seeks to distort the record of early Christianity as respects how early
Christians before the fourth century were opposed to the idea that they (loyal Christians) may serve in any earthly army.