12-ish was indeed the LEGAL minimum. It was not the SOCIALLY ACCEPTABLE minimum. It happened! But not often, and it was looked down on.
Super bluntly the younger the wife got pregnant, the more likely she was to DIE, and on top of that the baby will also die, and the mediaevals and early-moderns were VERY well aware of this, as they were also well aware that every single act of coitus is risking a pregnancy. You don't actually want to kill off your incredibly-valuable-political-alliance-token (ie: your wife, or your son's wife) via a pregnancy Too Young.
So in the upper ranks, while the wife might actually take off to live in the other dynasty's home at an earlier age, you can track both in writings and in dates of birth, and in social opprobrium for those who broke this norm, that you're still looking at ~18 or older.
Get lower in society and ahhahaha actually our average age of first marriage (ie: this has EXCLUDED the widows and widowers who are remarrying, so no they are NOT skewing the results) is mid-twenties. Sometimes, it's LATE twenties. Only in very specific boom times does it go down below that.
This is because the way that the culture worked, and the demands on a new household, you literally couldn't afford to do it before then. It would take you to that age to be ABLE to AFFORD to be married, because mediaeval and early-modern Western European and especially English society relied heavily on both genders as part of the economic unit that allowed a household to survive, and at that time actually really disapproved of wide age gaps in marriage.
This is a significant departure both from Antiquity (that tended to marry off much younger women to older men, because women really weren't part of the economic unit as much) and quite different from your period (where age gaps between husband and wife were increasing, probably in part because of the increasing industrialization of base-level production - that TENDS to be the thing that correlates, but obviously as you know bob correlation may not be causation**): in the mediaeval and early modern periods, marriages were usually between similar ages and that age was "in their twenties."
Again, the LEGALITIES were not that: it was LEGAL to marry (and consummate) as young as 12-ish (assuming she'd passed menarche) and there was nothing about age differences being a problem. But legality and social acceptability are two different things, and even social ACCEPTABILITY is very different from social NORM.
And socially we have a LOT of evidence that it was considered a really dick move (and one that implied you were a shitty husband and/or in-law) to have a teenage bride get pregnant; that age-gaps especially where the man was significantly older than the woman were Not Cool (and could end up with a rough music harassment - SIGNIFICANT and up to assault sometimes); and that you only BOTHERED with the marriage younger than the 20s if you had significant property you were trying to lock down, and even there sexual consummation was often delayed specifically because of the known risk.
Now note: this is very much Western-by-Northwestern Europe: Germania-Francia-Britannia (to name landmasses instead of countries because hahahaha), and Southern Europe was its own thing and had very different culture influences. This is part of why Shakespeare set Romeo and Juliet in Italy (Those Crazy Italians and their Crazy Thing With Marrying Off Babies), and you are still supposed to think that Paris and Capulet are being gross and creepy to marry off Juliet to an older man that young, it's just expected that Italians Are Weird And Creepy.
Speaking of which: Romeo and Juliet! Totally different play after deep-diving early-modern English culture, except then you come around and realize he literally told you in detail what the play was about in the prologue so it's weird that we miss it so much. (tl;dr: this play is about the Feud and the total failure of anyone to deal with the feud until it killed their babies, because they're Morons. The end.)
ETA: BUT ALSO - fwiw I have also seen the occasional fantasy commentator who has indeed probably been told some of this at some point and has interpreted this as "our age-of-consummation norms are accurate to the mediaevals" which is itself deeply stupid, in much the same way that the same kind of person often takes "actually mediaeval and early modern women were central to the economic unit and operated with a particular kind of significant influence/etc" as "mediaeval and early-modern culture weren't actually virulently misogynistic and anti-woman", which is ALSO not correct!
It's just more complicated and the simplistic formula of "well this was the norm in 1830 and The Past Was Worse so it must've been even worse in 1330" that gets applied is ALSO not going to steer you the right way; the society of 1330 might have hated women plenty, and it did, but it also needed a lot of them doing significant jobs in public to FUNCTION . . .and did, and humans being human most of these women turned around and took what power they could where they could, and so on.
Nobody was going to STOP eg the Duke of whatever from having sex with his twelve year old bride, but they were definitely going to JUDGE him for it, judge his father-in-law for allowing it, and consider it not something they were about to allow happen with their own daughter who definitely wasn't going off to the new ally's house until she was 16 and was going to go with her confessor and a retinue who were to Discourage Nuptial Visits until she'd been there a year or three.
The law wasn't going to STOP Old Man Miller from marrying 16 year old Elizabeth from the village but his house being surrounded by masked, torch-bearing locals chanting about his shame and not-so-subtly threatening to burn his house down might well make him think twice, or make her father think twice and keep her home until she was 20 and married one of the three 20yo men from the village instead.
And so on. And that did in fact change as we moved into the latter half of the 17th and into the early 18th century: women married younger and younger, and were also less and less part of the PUBLIC economic unit, all the more so the further up the ranks of society you went. It became different.
**(nb yes I know you said late 17th century ie 1670s-onward, not late 1700s, but even at that point COMPARED to eg 1450 production in food etc was moving towards a mass organized scale associated with what we call "industrial", which you probably know but I wanted to put here because I know some people might be like "1690 was way before the Industrial Revolution!" and like yes, but it was still increasingly industrialIZED compared to what came before)
no subject
12-ish was indeed the LEGAL minimum. It was not the SOCIALLY ACCEPTABLE minimum. It happened! But not often, and it was looked down on.
Super bluntly the younger the wife got pregnant, the more likely she was to DIE, and on top of that the baby will also die, and the mediaevals and early-moderns were VERY well aware of this, as they were also well aware that every single act of coitus is risking a pregnancy. You don't actually want to kill off your incredibly-valuable-political-alliance-token (ie: your wife, or your son's wife) via a pregnancy Too Young.
So in the upper ranks, while the wife might actually take off to live in the other dynasty's home at an earlier age, you can track both in writings and in dates of birth, and in social opprobrium for those who broke this norm, that you're still looking at ~18 or older.
Get lower in society and ahhahaha actually our average age of first marriage (ie: this has EXCLUDED the widows and widowers who are remarrying, so no they are NOT skewing the results) is mid-twenties. Sometimes, it's LATE twenties. Only in very specific boom times does it go down below that.
This is because the way that the culture worked, and the demands on a new household, you literally couldn't afford to do it before then. It would take you to that age to be ABLE to AFFORD to be married, because mediaeval and early-modern Western European and especially English society relied heavily on both genders as part of the economic unit that allowed a household to survive, and at that time actually really disapproved of wide age gaps in marriage.
This is a significant departure both from Antiquity (that tended to marry off much younger women to older men, because women really weren't part of the economic unit as much) and quite different from your period (where age gaps between husband and wife were increasing, probably in part because of the increasing industrialization of base-level production - that TENDS to be the thing that correlates, but obviously as you know bob correlation may not be causation**): in the mediaeval and early modern periods, marriages were usually between similar ages and that age was "in their twenties."
Again, the LEGALITIES were not that: it was LEGAL to marry (and consummate) as young as 12-ish (assuming she'd passed menarche) and there was nothing about age differences being a problem. But legality and social acceptability are two different things, and even social ACCEPTABILITY is very different from social NORM.
And socially we have a LOT of evidence that it was considered a really dick move (and one that implied you were a shitty husband and/or in-law) to have a teenage bride get pregnant; that age-gaps especially where the man was significantly older than the woman were Not Cool (and could end up with a rough music harassment - SIGNIFICANT and up to assault sometimes); and that you only BOTHERED with the marriage younger than the 20s if you had significant property you were trying to lock down, and even there sexual consummation was often delayed specifically because of the known risk.
Now note: this is very much Western-by-Northwestern Europe: Germania-Francia-Britannia (to name landmasses instead of countries because hahahaha), and Southern Europe was its own thing and had very different culture influences. This is part of why Shakespeare set Romeo and Juliet in Italy (Those Crazy Italians and their Crazy Thing With Marrying Off Babies), and you are still supposed to think that Paris and Capulet are being gross and creepy to marry off Juliet to an older man that young, it's just expected that Italians Are Weird And Creepy.
Speaking of which: Romeo and Juliet! Totally different play after deep-diving early-modern English culture, except then you come around and realize he literally told you in detail what the play was about in the prologue so it's weird that we miss it so much. (tl;dr: this play is about the Feud and the total failure of anyone to deal with the feud until it killed their babies, because they're Morons. The end.)
ETA: BUT ALSO - fwiw I have also seen the occasional fantasy commentator who has indeed probably been told some of this at some point and has interpreted this as "our age-of-consummation norms are accurate to the mediaevals" which is itself deeply stupid, in much the same way that the same kind of person often takes "actually mediaeval and early modern women were central to the economic unit and operated with a particular kind of significant influence/etc" as "mediaeval and early-modern culture weren't actually virulently misogynistic and anti-woman", which is ALSO not correct!
It's just more complicated and the simplistic formula of "well this was the norm in 1830 and The Past Was Worse so it must've been even worse in 1330" that gets applied is ALSO not going to steer you the right way; the society of 1330 might have hated women plenty, and it did, but it also needed a lot of them doing significant jobs in public to FUNCTION . . .and did, and humans being human most of these women turned around and took what power they could where they could, and so on.
Nobody was going to STOP eg the Duke of whatever from having sex with his twelve year old bride, but they were definitely going to JUDGE him for it, judge his father-in-law for allowing it, and consider it not something they were about to allow happen with their own daughter who definitely wasn't going off to the new ally's house until she was 16 and was going to go with her confessor and a retinue who were to Discourage Nuptial Visits until she'd been there a year or three.
The law wasn't going to STOP Old Man Miller from marrying 16 year old Elizabeth from the village but his house being surrounded by masked, torch-bearing locals chanting about his shame and not-so-subtly threatening to burn his house down might well make him think twice, or make her father think twice and keep her home until she was 20 and married one of the three 20yo men from the village instead.
And so on. And that did in fact change as we moved into the latter half of the 17th and into the early 18th century: women married younger and younger, and were also less and less part of the PUBLIC economic unit, all the more so the further up the ranks of society you went. It became different.
**(nb yes I know you said late 17th century ie 1670s-onward, not late 1700s, but even at that point COMPARED to eg 1450 production in food etc was moving towards a mass organized scale associated with what we call "industrial", which you probably know but I wanted to put here because I know some people might be like "1690 was way before the Industrial Revolution!" and like yes, but it was still increasingly industrialIZED compared to what came before)