I have been looking at my presumed Magna Carta descents, of which there are quite a number.
I am frequently seeing cases where a couple may have been married at a very young age, before their teenage years, and in quite a few cases as young as 3 years.
Sometimes there is a solid marriage date (ie, no qualifiers such as about or after), sometimes “before” a specified date. Birthdates are frequently estimates (“about”).
There are sometimes a citation to a secondary reference, which I do not have access to. But, never have I seen a primary source verification of a marriage of such young children.
I have seen historical references to marriage contracts and proxy marriages among the royalty, so I know it did happen.
How common were child marriages among the nobility or aristocracy?