This question has come up before.

I wrote an extensive answer here

Short answer: Whilst there was no special monetary compensation, in the early empire at least they would receive their full pension, which was a very respectable lump sum.

u/Astrogator offers some further details on wounded soldiers in answer to a follow-up question here

So first you have to define three terms: Roman, career, and soldier. Rome was a political entity that existed for a minimum of 900 years, and potentially as long as 1,800+ depending on how you view the Byzantine state.

By the wording of your question, I am assuming three things:

1. By 'Roman' you mean 'a legionary citizen of the late Republic or Principate,.'

2. By 'career,' I assume you mean 'foot soldiers not of the Equestrian or [Patrician](https://en.m.wikipedia.org/wiki/Patrician_(ancient_Rome) classes, ie plebs who would only serve as soldiers and would not be pursuing the cursus honorum'.

3. By 'soldier' I assume you mean 'serving during the time period between the Marian Reforms and the Crisis of the Third Century, or what might be loosely termed the 'classic' legionary period'.

With those definitions established, your question is relatively straightforward to answer. The historian Tacitus tells us that there were three different kinds of discharge from Roman service:

• the honesta missio, or retirement upon completion of service with full benefits
• the causaria missio, or retirement due to physical or mental incapacity
• the ignominiosa missio, or being dishonorably discharged for misconduct, mutiny, or crime (bad, but not enough to warrant execution or decimation)

So: to answer your question quickly, that soldier would get a pension, calculated then as now based on administrative assessment of severity of the injury, circumstances under which it was incurred, time in service, and any other factors that might come into play. Then as now, strictly non-critical factors such as how handsome the soldier, how heroic the action, how connected the family, etc. would have played a role. People are people, after all, and that won't have changed much in the intervening years.

However, this simple answer overlooks a couple of interesting additions. First, the role of disability in Roman culture was complex, and many disabling wounds may not have automatically seemed like cause for the causaria missio. For the Romans, innate disability (ie from birth) was a marker of moral shortcoming, and even some non-innate disabilities (eg a hunchback or limp caused by childhood injury) could lead to ostracization. The Twelve Tables included a law that said 'dreadfully' deformed children should be put to death, and during the Republic, disabled persons could not serve in the Army or hold public office.

However, not all disability was so punished. The Twelve Tables also noted that 'If one has maimed a limb and does not compromise with the injured person, let there be retaliation' and this even covered slaves. Honorably received wounds from soldiers were viewed positively - but establishing that could conceivably be difficult. For example, wounds in the back might be taken as running away, or psychological problems such as PTSD may not have been recognized as an injury.

It's also worth noting that we know a lot about this subject, thanks to a document called the pridianum (JSTOR link; sorry, hard to find any completely open sources), which was an annual strength report documenting the total number of soldiers in a given unit, as well as the nature of any losses or reinforcements sustained by the unit. Four still survive, so it's a great inside view.

Roman pensions were called praemia militiae (literally 'rewards for military service'), but they were only one of several benefits, including pay, rations, medical treatment, citizenship status (for auxilia) and/or land (for legionaries). Thanks to the pridianum, we know how they were calculated, how they were distributed, what percentage of the state budget they took up, and how they changed over time. We even know

During the Republic, funding came from the Senate. General practice then was much like today - legislatures are perfectly willing to pay for wars, less so for veterans. So the praemia grant tended to be land. During the Principate, the funding shifted to the aerarium militare, established by Augustus, and the praemia became a lump-sum payout. Some Emperors like Caligula lowered the amount, and others like Caracalla raised it, but this remained the standard right until the dissolution of the Empire.

Follow-up: Assuming by 'soldier,' u/Scrotie_ means Legionnaire, what would happen to an Auxiliary?

The short answer is that you would probably be given an honorable discharge, an honesto missio, and receive similar benefits to what a soldier would receive after a full career in the military. That could mean an exemption from Roman taxes, a plot of land with appropriate work animals, a job in the local imperial administration, or a cash payment.

The longer and more interesting answer is that it probably would have varied a lot throughout the incredibly long span of Roman history, and especially after the Roman military becomes professionalized in the Late Republic and beyond, so much of Roman history could be told through the story of emperors securing power by promising the best benefits package to the soldiers. Septimius Severus, who was able to survive the chaos of the Year of the Five Emporers, summed up that strategy when, according to Cassius Dio, he advised his sons to "be harmonious [with each other], enrich the soldiers, and scorn all other men."

So if you were a prominent general who was able to promise a better benefits package to disabled veterans, among others, you might just be able to leverage that into a dynasty.

The Roman Army: A Social and Institutional History discusses medical discharges on p. 164.