History of Roman Army Recruitment

[Calvo]

From the mid-republic to the late empire, the Roman army recruited its soldiers via different methods, and at each stage it experienced different problems.

The early-mid republic:
The legions were raised from an annual levy of eligible citizens who owned property, and the auxiliaries were supplied by allied cities and colonies. Every citizen was ready and willing to serve when the state required him to, and each campaign was merely a temporary interruption from civilian life. Nevertheless, during the Punic Wars mobilization rates were extremely high, with more than 1/3 of adult male citizens called up to the legions.

The late republic:
The legions were still raised by annual levies, but a "professional core" began to emerge from soldiers who had served long campaigns. After Marius abolished the property qualifications, many poor Romans enlisted in the legions as a means to make a living. Recruitment, on the whole, didn't seem to be a problem as the army provided a career, regular pay and a possible pension for millions of proletarian Roman citizens. Nevertheless, mass levies of a compulsory nature were still held to swell up the ranks during emergencies, such as the Social War, the civil wars and the Augustan conquests.

The principate:
The army was officially a professional institution with soldier serving 25-year contracts. The legions recruited Roman citizens, the auxiliaries recruited non-Roman natives. Although levies was still held every year, most recruits were volunteers (except during exceptions, such as the Rhine and Danube disasters), mostly because out of a total population of 50-60 million, the army had plenty of manpower to choose from. During times of peace, the army offered poor country people a steady income and medical services. As Roman citizenship spread away from Italy into the provinces, most of the soldiers became non-Italian, and more and more were drawn from sons of veterans.

After Diocletian:
After several plague epidemics and civil wars during the 3rd century, the population of the Roman empire was significantly reduced. After a major military reform, the army was expanded up to double its size, and of course, recruitment became more and more difficult.
Sons of veterans were obliged by law to enlist in the army, volunteers were paid special bonuses, but because military service had become so unpopular, the army still couldn't meet its annual quotas and had to make up its numbers via conscription. Many Germans from outside the empire enlisted, who by the 4th century had formed a significant minority of the Roman army.

The reasons as to why military service had become unpopular in the late empire remains a mystery. At least on paper, service conditions were certainly no worse than during the principate: salaries were raised several times (or had the real worth gone down?), land grant was given on discharge, soldiers were allowed to marry and even live outside the fortress with their families. For most people in the countryside life wouldn't have become too comfortable either to make a military career seem too unattractive.
Or was it that potential fighting men found other professions where they could make a more generous income?

[M. Caecilius]

The early-mid republic:
The legions were raised from an annual levy of eligible citizens who owned property, and the auxiliaries were supplied by allied cities and colonies. Every citizen was ready and willing to serve when the state required him to, and each campaign was merely a temporary interruption from civilian life. Nevertheless, during the Punic Wars mobilization rates were extremely high, with more than 1/3 of adult male citizens called up to the legions.

Just to add that there were periods when citizens were less than willing to serve. Livy reports several incidents at the annual levies, in particular where campaigns in less booty-rich and protracted wars were concerned. And then there is the long debate on whether the effects of longer campaigns were as serious as the Gracchi claimed. After all, many people stood to lose from unrewarding campaigns, considering only property owners were eligible (and then again, even before Marius there were times when proletarians and even slaves were allowed to join the legions - though mostly only in the direst of emergencies).

The reasons as to why military service had become unpopular in the late empire remains a mystery. At least on paper, service conditions were certainly no worse than during the principate: salaries were raised several times (or had the real worth gone down?), land grant was given on discharge, soldiers were allowed to marry and even live outside the fortress with their families. For most people in the countryside life wouldn't have become too comfortable either to make a military career seem too unattractive.
Or was it that potential fighting men found other professions where they could make a more generous income?

I wonder whether concessions made to soldiers - especially the one giving them the right to marry - were not part of a move to make service more appealing. Although long before that law was introduced, soldiers seem to have happily ignored the fact that they were not allowed to marry and had wives and children anyway... whatever the law thought.

As for the unpopularity of military service in the later empire, I would take into consideration that the risks had increased. There were far more wars, and increased raids, than there had been before, and hardly any involved making booty, after Trajan. As far as salaries go, they did go up, but as you say, the actual worth may have gone down. Rome was caught in something approaching hyperinflation if you are looking at the coinage of the time, and harsh (if futile) measures such as the Edict on Maximum Prices. If I recall correctly, Rome also shifted from paying soldiers (and gathering taxes) in kind rather than coinage at some point, but I'm a bit hazy about that.

Also, I wonder whether the recruitment of Germanic and other soldiers was the outcome of recruitment problems amongst the Empire's own citizens, or contributed to it, because those who felt they were "true" Romans no longer saw the army as prestigious enough if they had to share rank and status with barbarians. Not that citizenship meant as much after the Constitutio Antoniniana as it had before.

[Quintius Clavus]

With the rule of Augustus and his military reforms, the army (and the armed forces including the fleets) became the emperor's problem and responsibility. How much of the purported panic after the Varus defeat was really just Augustus' panic and not felt by the average Roman in the street, except that it then subjected him to possible service in distant places to which he had NO desire to go? Emergency call-ups in Italy due to the Pannonian rebellion and the Varus defeat resulted in some resistance and forced conscription, with threats up to and including the death penalty for failure to step forward. Tiberius complained that recruiting in Italy resulted in only the destitute coming forward.

Conscription existed right along side voluntary recruitment. For a while at any rate, new legions seem to have been raised in Italy, but what inducements were used to get the men to volunteer, is unknown at least to me.

Harsh discipline and serving in places like the Germanies, or Britain or along the Danube, may have made service less attractive for some at least. IIRC, one of the rumors floating about, which influenced the support of the eastern legions for Vespasian, was that the western troops would be rewarded by Vitellius with eastern postings and the eastern legions sent to take their places along the Rhine. Needless to say, the eastern legions wanted no part of postings on the Rhine. Horrors, it gets cold there and by the way those nasty Germans are hard to kill! Besides they had formed strong attachments in the communties near whch they served. Summerly's thesis on the centurionate mentions that being able to speak Greek was important for centurions posted to the eastern legions.

Desertion was a perennial problem in peacetime and in wartime. Some of those deserters turned to lives of crime, brigandage also being a major problem and putting such down may have taken an increasing role in the tasks of the army.

The citizen cavalry of the Republic became essentially mercenary cavalry (hired for campaigns) because young equestrians no longer had any desire to be common troopers and there was money to be made in commerce, tax farming, etc. Why risk a sword or spear being stuck into you?

[Timianus]

I also think it is important to consider the social/economic strata during the late imperial period. Since the end of the republic, there was a trend where the "middle class" farmer (the mainstay of the republican army) was basically eliminated. An increasing number now worked under indentured servitude contracts to very wealthy large villa owners. These very wealthy aristocrats were able to avoid having their "employees" recruited; hence the concern that conscription turned up only the destitute. Also consider the difference in martial vigor and conditioning between a farmer and a malnourished city-dwelling destitute.

[Calvo]

Conscription existed right along side voluntary recruitment. For a while at any rate, new legions seem to have been raised in Italy, but what inducements were used to get the men to volunteer, is unknown at least to me.

Problems with finding recruits during the early empire only seemed like an occasional problem that arose under exceptional conditions, such as the disasters you mentioned, but on the whole, recruiting the legions up to strength didn't seem to pose a great problem for the authorities before the end of the 3rd century A.D..

As in all societies throughout history, poor people who lived at subsistence level had always provided the best military material, as life as a professional soldiers provided them a steady income, clothing, and all the basic needs. Regarding the risk of death, the probabilities of dying of disease and hunger as an undernourished civilian were probably greater than dying of a sword as a soldier, considering the harsh living conditions of a farm labourer in the countryside or a slum dweller in the city.

As far as citizenship was concerned, it has been known that in times of dire necessity, thousands of non-citizens were granted with Roman citizenship in order to be recruited into the legions.

[Calvo]

Despite all the recruitment difficulties of the Roman Empire throughout the 4th and 5th centuries, what is surprising is that by the 6th century, the problem seems to have been resolved.
During Justinian's conquest, he raised a campaign army without apparrently any difficulties, and recruitment seemed to be largely voluntary, as no mention of conscription or hereditary enlistment was mentioned in the Justinian code.

Was recruitment, by the end of the day, only a problem of the western empire while in the East they always found an abundant source of manpower? Or was there any major demographic or socioeconómic changes between the 4th and 6th centuries to make military service an attractive career to many people again?