How did "oxen" (plural of "ox") survive as the only plural form with the Old English plural ending -en?

Question

Oxen is a rare exception in English where it is the only common English word that retains the original Old English plural ending -en. (Note: Children and brethren are formed a bit differently, please see the note at the end.)

Etymonline has this explanation for oxen:

plural of ox, it is the only true continuous survival in Modern English of the Old English weak plural (see -en (1)). OED reports oxes occurs 14c.-16c., "but has not survived."

The usage of the plural form oxes can be seen as far as the year 1905 per the latest citation in OED with a plural form of ox.

1905 Hitch my oxes To de plow.
_{A. V. Culbertson, Banjo Talks 41}

_{Oxford English Dictionary, s.v. “ox, n., sense 1.a”, July 2023. https://doi.org/10.1093/OED/9070656295}

OED lists the plural forms below for different periods:

Period	Plural form
Old English	oexen (Mercian), oxan
Old English–Middle English	exen, exin
Old English–	oxen (rare)
Middle English	exon, ocsen, oksen, open (transmission error), oxene, oxis, oxnen, oxon, oxone, oxsen, oxsyn, oxun, oxys
Middle English–1500s	oxin, oxyn, oxyne
Middle English–	oxes (now regional)
1500s	oxeson
1800s–	oxens (U.S. regional)

_{Oxford English Dictionary, s.v. “ox, n., Forms”, July 2023. https://doi.org/10.1093/OED/2903238464>}

Note that, oxen is mentioned as rare in Old English even, and the plural form oxes survived till modern English period per the citations in OED. There aren't any citations with oxen after the latest citation with a plural form of ox (as oxes) from 1905 in OED. Vocabulary.com has this brief history about -s and -en plural forms:

You may have heard that English is a Germanic language. The -en ending on plurals is something we get from our German roots. In Old English, some nouns were made plural with -s and -es as they are today, but many nouns took -en to become plural.

The s-form plurals became dominant in northern England first, while the en-form hung on in southern England. By the 14th century the s-form became dominant everywhere, but people didn't let go of the en-form completely; as late as the 16th century the plural of eye was eyen and the plural of hose was hosen. Today only a few en-forms survive; the most common are oxen and children.

The above explanation doesn't exactly answer the question though. What happened in history that oxen has become the accepted plural form? Did the southern usage gain traction in time; and if yes, how? Could there be an influential work or writer (from 1900s or earlier) that revived or popularized the usage oxen?

---

Note: Children and Brethren are other similar exceptions but they don't have the pure plural form with -en and their formation is a bit different than oxen. OED has this note for the plural word children:

In early Middle English, the r-plurals (see Forms 2aγ) are affected by the spread of the (originally weak) plural -en in southern English (see -en suffix³), yielding the double plural children (see Forms 2aδ), which becomes the usual form in southern dialects of Middle English and in modern standard English (compare likewise the development of brethren, plural of brother n.).

_{Oxford English Dictionary, s.v. “child, n., Etymology”, July 2023. https://doi.org/10.1093/OED/2625064881}

---

The question linked below is related and it has a good answer, but I'm asking something different:
Etymology of certain words ending in "-en"

Answer 1

Old English oxan, plural of oxa, was very common, appearing in the psalter, the bible, and laws, among other places, although the spelling oxen is attested in only one place, in a document relating to Bury St Edmund's possessions, rents, and grants.

The genitive plural form of oxa, often with a syncopated vowel, was ox(e)na. That genitive form is attested in place names (cf. oxenaford, Middle English Oxenford, ModE Oxford, oxeneham ModE Oxnam, oxenesetene ModE Oxsettle Bottom, oxnaleage ModE Oxleigh and Oxley , a woodland clearing or a natural glade, meadow, lea, a plant name oxna-lib glossing Latin oleotropius ModE oxlip, ox-heal), as a unit of measure of land (oxnagang, ModE ox-gang, one-eighth of a "hide"), and in genitive (oxna-paeþ ModE oxens' path) and partitive genitive constructions (ic bohte fif getymu oxena, ic bohte an getyme oxena, ModE I bought five teams of oxen, I bought one team of oxen) and those uses appear not only in texts dealing with quotidien farming and mercantile situations but notably in passages from the Bible, which would frequently have been heard by audiences from all social and economic classes.

The plural appears as oxen and is very well-attested in Middle English in a wide range of texts. It appears in various spellings, including oksen, exen, oxon, oxen, oxsen, oxsin, ocsen (see the MED). Its appearance in proverbial contexts (Moche uolk of religion zetteþ þe zuolȝ be-uore the oksen. Many people of religion set the plow before the oxen) and laws is very strong evidence that it was widely used.

P.S. I have a copy of the Old English corpus and found these attestations by searching it. (I studied Old English and Middle English as an undergraduate and graduate student, back before the days of personal computers, but they haven't changed much in the interim.)

P.P.S. I stumbled upon a book, Working Oxen by Martin Watts. 1999. "... a survey of their use in Britain, their impact upon the countryside, and the relics that can still be found: yokes, bows, shoes, housing and place-names. Martin Watts is curator of the Ryedale Folk Museum in North Yorkshire." [Google Books description] and "Oxen were one of the most important sources of motive power in the British countryside... The working ox has left a lasting mark on the language, landscape and culture... Historians rarely mention or study them. It is as if a history of twentieth century were to ignore the impact of the tractor and the lorry. The purpose of this book is to redress that balance." [from the blurb on Amazon].

Answer 2

I don't know of any satisfying reason for it.

Note that when the OED says "Old English– oxen (rare)", it means that the specific spelling O-X-E-N was rare in Old English. It doesn't say that oxan was rare, and from the point of view of later development, the difference between Old English oxan and oxen is irrelevant: it was normal for Old English "a" in unstressed syllables to be weakened to schwa, which in Middle English came to be spelled "e". Compare the development of the Old English infinitive ending -an to -e in the case of words like drīfan > drive.

There is a general principle that irregular forms persist longer in frequently used words, but I'm not sure how much it can do to explain the use of the form oxen. I don't think we talk about oxen as much as we used to.

It seems conceivable that the fact that the singular already ends in an /s/ sound made it a bit harder for the sibilant plural to become established, but I'm not really sure if that played an important role: obviously there are multiple other words ending in -x that do form their plurals in -xes, such as foxes, boxes, axes.

Answer 3

There has been a certain geek revival of this construction in regexen and VAXen. It started as hard ironic but has become mainstreamish for regexen. Um, as mainstream as anything involving regex can be. (The DEC VAX line is 20 years obsolete so VAXen is mainly a feature of old-timer stories to emphasize that they're old-timer stories. A server room becomes a "herd of VAXen.")