My heroine is a secret agent who travels with one of Emperor Hadrian’s legions disguised as a camp launderer. (For context, she’s not spying on the legion or anything, but her mission is secret.) Could she feasibly hide Roman armour under civilian clothes?
So, before we fully pry this question apart, the simplest answer is, “no, you cannot hide armor under civilian clothes.” This isn’t, 100% true. In the modern era you can conceal a light ballistic vest under heavy clothing, like a hoodie or jacket. It will still add bulk, but not to the point that you automatically assume they’re wearing armor.
When we’re talking about historical armor, the answer will, generally, be, “no.” In the case of a Roman Legionary, no, you could not.
A spy may have armor that functions as their uniform when they’re on home territory and openly interacting their military. Which is a long way to say, “yes they may have armor back at home,” but they probably wouldn’t bring it with them.
Also, I’m not an expert on the Roman Legions, but, my understanding was that the Legions on the move did not employ dedicated launderers. Laundry duties were performed along with bathing, and a Legionary was responsible for cleaning their own gear. The Legatus might have had a personal servant who handled their laundry, but I’m just guessing there, and that’s a long way from “the camp launderer.”
There were a number of potential intrigues within a legion. The Legion had 120 Eques Legionis, who were mounted cavalry, and their duties included scouting and relaying messages. As covers go that grants a lot of latitude for independent operation.
The Tribune was appointed by the Emperor as the Legion’s second in command (behind the Legate.) It’s possible (even under Hadrian) that the Tribune may have covert orders from the Emperor.
Additionally, there were the Immunes. These included surgeons, Venetorii (hunters), engineers, and other specialist roles. If someone had technical training that the legion used (even in its civil functions) they were probably an Immune. This mean they were exempted from the hard labor that most Legionaries engaged in.
Civilian camp followers offering laundry services was a reality, historically. But, that was (mostly) later in the middle ages. Camp followers were a serious weak point, as you had civilians following armies, without much scrutiny. They didn’t have access to the camp, proper, but they did have a lot of access to its soldiers, which was almost as good for intelligence gathering.
When it comes to women in the Roman Legions, they weren’t allowed to serve. Until recently, archaeologists have taken this to mean there were no women. Additionally, Hadrian’s rule came in the middle of a two century ban on married legionaries. (Note: I do mean the soldiers. This ban did not extend to officers.) So, on paper, these were supposed to be unmarried men. However, the legionaries would marry illegally. Archaeological research at Vindolanda (an auxiliary fort along Hadrian’s Wall), estimates that ~43% of the legionaries stationed there had a wife or children.
There is a problem: The Legionaries weren’t paid enough to support the families they weren’t supposed to have, so the women worked. It’s believed that the women were employed in domestic roles such as fort cooks and launderers. As a random note: Immunes received better pay than their fellow soldiers. Though, I suspect it still wasn’t enough to support a family.
So, this is not a Roman legion on the move, and more importantly, these jobs would have preferentially gone to the Legionary’s wives, not a Roman citizen showing up under strange circumstances.
Also, while you’re looking for something, it is worth remembering that the senior officers may have had family members present. Especially if they were deployed someplace for decades.
So, that’s the legion, let’s talk about spies, cover identities, and gear for a second.
When you’re picking gear for a spy, you need to consider their cover identity, and mission critical equipment. Nothing else. This is something we’ve discussed before, though that was about assassins. In many cases this means they neither need, nor benefit from, having weapons and armor.
If your job is to kill someone, you need a weapon. Okay, “need” is debatable, but you will seriously benefit from having one. Ironically, most people don’t carry functional weapons on a daily basis. It has been the fashion historically, and it’s not too hard to explain away a knife as a utility tool, but if your job as a spy doesn’t include combat, that weapon doesn’t help you do your job.
Likewise, most people don’t wear functional combat armor on a regular basis. If your spy is not in a role where that armor would be expected, it’s a major sign that something isn’t, quite right. The armor is, literally, more dangerous to a spy than its absence would be. Obviously, if you’re in a fantasy setting you might have armor options that wouldn’t be out of place for your cover, but that requires roles that are far rarer in the real world.
I suspect you thought about this, but when your spy is trying to set up a cover, they want one that will overlap with their actual job as much as is practical.
If you need to get information from someone important, get hired onto their personal staff. Preferably a position that will get you the access you need, so that when you need to extract with the information, you can pick it up and walk out the door without anyone thinking anything’s amiss.
The reason that service positions make for excellent covers is, they allow your spy to eavesdrop as part of their job. No one will question a waiter listening in on a conversation periodically, because their job requires them to know when the patrons need something from them. Getting caught isn’t the end of the world, because their behavior has the potential to be legitimate.
Additionally, most service positions are functionally invisible to the average person. If you interact with a lot of people on a daily basis, people who provide these services just kinda blend into the background. (Now, obviously, if you’re interacting with the same person for years, you’re more likely to remember them.)
Within this context, launderer isn’t as good. Because you will be tethered to the cover, and you’ll need to spend a lot of your time away from the people you’re trying to eavesdrop on. This doesn’t mean it’s a bad cover, just that options are more limited. Also, critically, you’ll probably to move away from the cover to do your real job, this is a problem. This makes your spy more noticeable. Nobody notices a bartender when they’re behind a bar, but when you see them sneaking into someplace across town, they’re going to stand out.
Maintaining a cover, really is, about looking legitimate until the last possible moment. Your character needs to pretend to be doing the job they’re supposed to, playing that role. Get caught out of character and it’s over.
To give your character the best position possible, she should probably be sent with the Legion along with the Tribune. Maybe assigned as his daughter (maybe actually his daughter.) That would give her a lot of autonomy, a lot of inferred authority, without any of the responsibilities, and a cover that will let her (almost) get away with murder.