I'm planning for a scene where a family of medieval nobles and their accompanying party are ambushed while traveling through the countryside. For plot purposes I need to separate the noble woman from her ten-year-old son and newborn baby at the moment of attack. The first solution that came to mind was to have her seek privacy to relieve herself. But then I thought, "How would a medieval noble woman ask for that?" Maybe. "Dear, nature calls." Or "I have held my water for far to long." She's well-bred and well-mannered, so keep that in mind. Also, if she excuses herself to pee, would her husband then accompany her into the woods? The surrounding country is known to be infested with dangerous folk. I should note she needn't have to relieve herself if a I can come up with a better way to put some significant distance between her and her children at the moment of the ambush.
Update: After a bit more thought I managed to come up with a way to separate everyone after the attack, so the whole relieving oneself solution is thankfully no longer needed.
I know you don't need it now, but I imagine people were less prissy about bodily functions back in medieval times, than they have been since Victorian times. They were probably quite straightforward about the need to pee and shit. However, especially as the situation while traveling was dangerous, I do imagine she would be accompanied ...if not by her husband, at least by her female attendants. (Who probably needed to go themselves!)
I was going to say the same - if you read Tim Willocks, the twelve children of paris, which is about the massacre of the Huguenots in the 15oos theres a scene where a noble woman is relieving herself under the stairs in the palace... although this is fiction willocks did a lot of research and notes in the afterword that since germ theory wasn't a thing it was quite usual for nobles to simply pee and crap anywhere out of sight... when the smell got too bad the court simply moved to another palace
If she's got a newborn baby, it's unlikely a noblewoman of any pre-Modern period would be travelling anywhere, unless it's a dire emergency. And in the crisis you describe, if it were me, I'd be desperately searching for my kids, and to hell with relieving myself. But maybe the bandits (or whatever they are) have her in custody and are withholding the children from her. I doubt they'd let her seek privacy to piss, unless they were impossibly gentlemanly marauders. They'd direct her to squat where she was, and make her put up with the smell thereafter. Keep in mind that women wore no underpants till the late 1700s, early 1800s. And when underdrawers became a thing, until the 1880s or so they really were a "pair," two separate legs attached at the waist and tied on, with no crotch. In general, your sans-pants medieval lady would have no fear of immodesty in relieving herself; all she'd have to do is find a place where she could squat and spread her long skirts out a bit. You can see the kind of clothes she'd be dealing with here: "500 Years of Medieval Fashion." If she's permitted to withdraw to make water in the woods, the difficult thing would be coming by a damp cloth or sponge to wipe with. We can sympathize with her plight in our own time, with our virus-panicked neighbors hoarding all the toilet paper. Though tree leaves or a wad of grass was always an option. For her or for us? Take your pick.
Moss was used by the Celts as toilet paper (and it is very good toilet paper, had the chance, or mischance, to have to use some when I went camping once). Very absorbative. However, if it is a known bandit area, then I would think the husband would accompany her. Also, if she is a noble women or rich, she would have a wetnurse/nurse to look after the newborn. She may also be in charge of the other 10y.o child. Highwaymen at the time would often rob carriages, however they were typically not resisted by the coach drivers. Some even pulled up so they could do their business and leave. It seems unlikely that she would seperate herself willingly.