Beowulf is an early poem out of a lost world. In a very important way, that was already true in turn-of-the-millennium Wessex. By the time the Nowell Codex was produced around 1000 AD, written Old English itself was probably a somewhat more "artificial" language than it had been in the pre-Alfredian period. The language of Old English verse in particular was rather removed from anybody's everyday speech, doubly so in this poem, one of the oldest to have survived.
An atmosphere of undatability and dialectal unplaceability surrounds this poem for many. Arguments that the poem might be a very late composition have been father to a bit of a bastard agnosis about it.
How that came to be is a long story. But, regardless of what went on in literature departments, there has never been a Beowulf dating controversy in linguistic scholarship. Unlike literary scholars, most linguists have in fact never found a late date even credible. As Fulk put it, linguists were not only "largely untouched by the controversy" surrounding the date but for far too long didn't bother dignifying it with a particularly serious response. Linguistic literature on archaism in Beowulf from about 1980 to around 2015 has a few footnotes on the controversy in which the eye-rolling is pretty palpable.
The position is well-founded. Not only do many lines only scan properly if one substitutes Mercian forms, but the copyists either didn't care or didn't notice. Several able studies have shown that the scribes of our text were insensitive to the metrical principles that the actual poet/s operated with. Beowulf's versification is unique in being so consistently sensitive to distinctions of vowel length in unstressed syllables. There is also exhaustive evidence that the scribes often had a hard time understanding what they were reading. They misread proper names that had not been common for two centuries, and sometimes found Anglian dialect forms baffling. This evidence and much more besides (from the chronology of Old English poetic syntax to the changing onomasticon of Anglo-Saxon England in the 9th century) all conspires to support one conclusion: the language of Beowulf is genuinely archaic. It is the product not of a late poet’s attempt to recreate an early style, but of an extremely old tradition that had largely vanished by the time the extant Old English manuscripts were created.
Based on dialect forms, scribal errors and metrical sensitivity to vowel-length in inflections, the ablest philological conclusion is that this text was composed in some form of Mercian some time between roughly 690 and 725. That is pretty good resolution, relatively speaking. But it still leaves open a considerable range of possibilities.
Nonetheless, here (in case anyone finds it useful) is one plausible version of what the first couple hundred lines may have looked like in Early Mercian, if it were edited into an edition.
(Frumscæft)
Hwæt wé gár-dæná in ġár-dagum
þéod-cyningá þrymm gifrugnun,
hú þá æðilingas ellin fræmidun.
Oft sceld scéƀing sceaðæná þréatum,
monegum mégðum medu-setlá oftáh,
egisadǽ Iorlí. Siþþan ǽrist wearþ
féascæft fundæn, hé þæs fróƀrǽ gibád.
wéx undær wolcnum, weorþ-myndum þáh,
oþþaet him œ́ghwelc þér ymb-sittændrá
oƀær hron-rádǽ héran scoldǽ,
gomban geldan. Þæt wæs gód cyning
Ðǽm aƀurá wæs æftær cænnid
ġung in geardum þonǽ god sændǽ
folcǽ tó fróƀrǽ; firin-þearƀǽ ongæt,
þæt híæ ǽr drugun aldur-léasǽ
longǽ hwílǽ. Him þæs líƀ-frëá
wuldræs waldænd weruld-árǽ forgæƀ:
Bíowí wæs brœ́mí – bléd wídǽ sprong –
Sceldæs aƀurá scedi-londum in.
Swé scæl ġung gumá gódǽ giwirċan
fromum feh-giftum on fæder bearmǽ
þæt hinǽ on ældǽ eft giwunigæn
wil-gisíðas, þonnǽ wíg cumǽ
líodí gilǽstæn: loƀ-dédum scæl
in mégðá gihwǽm monn giþíän.
(Sceldæs Ferhgidál)
Him þá Sceld giwát tó giscæp-hwílǽ,
felu-hrór fœ́ran on fréan wérǽ.
Híæ hinǽ þá ætbérun tó brimæs faruðǽ,
swésǽ gisíðas, swé hé selƀá bæd,
þændæn wordá giwald Wini Sceldingá
léoƀ lond-frumá longǽ ǽhtí.
Þér æt hýðǽ stód hringid-stefná,
ísig ænd útfús, æðilingæs fær.
álægdun þá léoƀnǽ þéodæn,
bégá bryttan on bearm scipæs
mérnǽ bi mæstǽ. Þér wæs máðmá felá
of feor-wegum frætwá gilǽdid,
ni hérdǽ ic cýmlicor céol gigerwan
hildí-wépnum ænd haðu-wédum,
billum ænd byrnum; him on bearmǽ læg
máðmá mænigu þá him mid scoldun
on flódæs ǽht feor giwítan.
nallæs híæ hinǽ lǽssan lácum tíodan
þéod-gistréonum þonnǽ þá dédun
þe hinǽ æt frumscæftǽ forþ onsændun
ǽnnǽ oƀær ýðǽ, umbr-wesændí
Þá gét híæ him ásettun segn gyldænnǽ
héh oƀær héaƀud, létun holm beran,
géƀun on gársecg. Him wæs ġómor seƀá,
murnændí mód. Mæn ni cunnun
secgan tó sóðǽ seli-rédændí
hæliþ undær heƀunum hwá þǽm hlæstí onféng.
(Of þǽm strængǽ cwómun æftærcyningas)
Þá wæs on burgum Bío Sceldingá,
léoƀ líod-cyning, longǽ þrágǽ
folcum gifrégí (fæder ellur hwearƀ,
aldur of eardǽ), oþþæt him eft onwóc
héh Halƀdæní; héold þændæn liƀdǽ,
gomol ænd gúðréow, glædǽ Sceldingas.
Þǽm féowur bearn forþ-girímid
in weruld wócun, werudá réswan,
Herugár ænd Hróðgár ænd Hálgá til;
hérdǽ ic þæt Ýrsǽ wæs bi Onalan cwœ́n,
Haðu-scelƀingæs hals-gibeddá.
(Heorotæs gibytlung)
Þá wæs Hróðgárǽ heri-spœ́d geƀæn,
wígæs weorð-mynd, þæt him his wini-mágas
geornǽ hérdun, oþþæt sío ġuguþ giwéx,
magu-dryht micil. Him on mód bi-arn
þæt hal-reccid hátan woldǽ,
medu-ærn márǽ, mæn giwircan
þonnǽ ældá bearn ǽfrǽ gifrugnun,
ænd þér on innan all gidǽlan
ġungum ænd aldum, swelc him god saldǽ,
búton folc-scærǽ ænd ferhum gumaná.
þá ic wídǽ gifrægn werc gibonnan
monegrǽ mégþǽ ġond þisnǽ middan-geard,
folc-stedi frætwan. Him on firstǽ gilomp,
édrǽ mid ældum, þæt hit wearþ ælgearu,
hallærná mǽst; scóp him Heort noman
sé þe his wordæs giwald wídǽ hæƀdǽ.
Hé biát ni álég, bégas dǽldǽ,
sinc æt simlǽ. Seli hlíƀadǽ,
héh ænd horn-géap, haðu-wælmá bád,
láðan lígæs; ni wæs hit læṅgǽ þá gén
þæt se ecg-heti áþum-swéoran
æftær wæl-níðǽ wæcnan scoldǽ.
(Cymþ se Gǽst)
Þá se ellurgǽst earƀuðlícǽ
þrágǽ giþoladǽ, sé þe in þíostrum bád,
þæt hé dógrá gihwǽm dréam gihérdǽ
hlúdnǽ in hallǽ; þér wæs hearpan swœ́g,
switul song scopæs. Sægdǽ sé þe cúðǽ
frumscæft firhá feorran reccan,
cwæþ þæt se ælmæhtġá eorðan worhtǽ,
wliti-berhtnǽ wong, swé wæter bibúgiþ,
gisettǽ sigi-hrœ́ðig sunnan ænd mónan
léoman tó léhtǽ lond-búændum
ænd gifrætwadǽ foldan scéatas
léomum ænd léaƀum, líƀ éc giscóp
cynná gihwelcum þárá þe cwicǽ hwerƀaþ.
Swé þá dryht-guman dréamum liƀdun
éadiglícǽ, oþþæt án ongon
firinǽ fræmman fíond on hellǽ.
Wæs se grimmá gǽst Grændil hátæn,
mérí mærc-stapá, se þe móras héold,
fæn ænd fæstæn; fífl-cynnæs eard
won-sélig wer weardadǽ hwílǽ,
siþþan him sceppænd forscriƀæn hæƀdǽ
in Camæs cynnǽ. Þonǽ cwalm giwræc
écí dryhtin, þæs þe hé Ábel slóg;
ni gifeh hé þǽrǽ fǽhðǽ, ac hé hinǽ feor forwræc,
metud forǽ þý mánǽ, mon-cynnǽ from.
Þanon untýdras allǽ onwócun,
etunas ænd ælƀí ænd orcnëas,
swelcǽ gígantas, þá wiþ godǽ wunnun
longǽ þrágǽ; hé him þæs léan forgald.
(First Hráfyll)
Giwát ða níosan, siþþan næht bicwóm,
héän húsæs, hú hit Hringdæní
æftær béorþegǽ gibún hæƀdun.
Fond þá þér-innǽ æðilingá gidryht
swefan æftær simlǽ; sorgǽ ni cúðun,
wonscæft werá Wiht unhǽlu,
grim ænd grédig, gearu sóná wæs,
réc ænd rœ́ðí, ænd on ræstǽ ginom
þrítig þegná, þanon eft giwát
húðǽ hrémig tó hám faran,
mid þǽrǽ wælfyllí wícá níosan.
þá wæs on úhtan mid ǽrdægǽ
Grændlæs gúðcræft gumum underní;
þá wæs æftær wistǽ wóp up áhæƀæn,
micil morgin-swœ́g. Mérí þéodæn,
æðiling ǽr-gód unblíðí sæt.
Þoladǽ þrýð-swíþ. Þegn-sorgǽ drég
siþþan híæ þæs láðan lást scéawadun
wærgan gǽstæs. Wæs þæt giwin tó strong
láþ ænd longsum. Næs hit læṅgrá first
ac ymb ánǽ næht eft gifræmidǽ
morþ-bealu márǽ, ænd ná mearn forǽ,
fǽhðǽ ænd firinǽ: wæs tó fæst on þǽm.
(Egifitt)
þá wæs éðfyndí, þe him ellæs hwér
girúmlícor ræstǽ sóhtǽ,
bed æftær búrum, þá him gibécnud wæs,
gisægd sóðlícǽ swetulan tácnǽ
hall-þegnæs heti: héold hinǽ siþþan
firr ænd fæstor se þǽm fíond ætwond.
Swé ríxadǽ ænd wiþ rehtǽ won
áná wiþ allum oþþæt ídel stód
húsá sélist. Wæs sío hwíl micil:
twelf wintrá tíd torn giþoladǽ
wini Sceldingá, wéaná gihwelcnǽ,
sídrá sorgá. For þǽm giséní wearþ
ældá bearnum, un-derní cúþ
geddum ġómrǽ, þætte Grændil won
hwílǽ wiþ Hróþgár, heti-níðas wæg,
firinǽ ænd fǽhþǽ, felá missirá(?)
singálǽ sæccǽ. Sibbǽ ni woldǽ
wiþ monná hwonǽ mægnæs Dænigá
ferh-bealu firran, feo(h)ǽ þingian,
ni þér nǽnig witaná wénan þorftǽ
berhtrǽ bótǽ tó bonan folmum
ac se æglǽcá œ́htændí wæs
derc déaþ-scúá, duguðǽ ænd ġuguðǽ,
semadǽ ænd seridǽ. Sinnæhtí héold
mistgǽ móras. Mæn ni cunnun
hwider hel-rúnan hwyrftum scríðaþ.
(Heorot Gihergod)
Swé felá firiná fíond moncynnæs
atul ángæṅgá oft gifræmidǽ,
heardrá hénðá. Heorot eardadǽ,
sinc-fágǽ sæl sweartum næhtum.
Ná hé þonǽ gifstól grétan móstí:
máðm formetadǽ ni his myni wissǽ.
Þæt wæs wræc micil, wini sceldingá,
módæs brecþá. Monig oft gisæt
rící tó rúnǽ, réd æhtadun ,
hwæt swíþ-ferhþum sélist wérǽ
wiþ fér-gryrí tó gifræmmænnǽ.
Hwílum híæ gihétun æt hærgtraƀum
wíh-weorðungǽ, wordum bédun
þæt him gǽst-baná ġucǽ gifræmidǽ
wiþ þéod-þréawum. Swelc wæs þéaw hirá,
hǽðinrá hyht: hellǽ gimundun
in módseƀan; metud híæ ni cúðun,
dédá dœ́mænd. Ni wistun híæ dryhtin god,
né híæ húru heƀoná helm herian ni cúðun,
wuldræs waldænd. Wá biþ þǽm-þe scæl
þurg slíðnǽ níþ sáwlǽ biscúƀan
in fýræs fæðm, fróƀrǽ ni wénan
wihtí giwændan. Wél biþ þǽm-þe mót
æftær déaþdægǽ dryhtin sœ́can
ænd tó fædr fæþmum friðu wilnian.
Swé þá mél-cearǽ magá Halƀdænæs
singálá séaþ. Ni mæhtǽ snotr hæliþ
wéan onwændan: wæs þæt giwin tó swíþ,
láþ ænd longsum, þe on þá líodí bicwóm,
néd-wracu níþ-grim, næht-bealwá mǽst.
(Hæliþ wé þearƀiaþ)
Þæt from hám gifrægn Hygilácæs þegn,
gód mid Géatum, Grændlæs dédá.
Sé wæs mon-cynnæs mæginæs strængist
on þǽm dægǽ þissæs líƀæs,
æþilí ænd écen. Héht him ýþ-lidan
gódnǽ gigerwan: cwæþ, hé gúþ-cyning
oƀær swon-rádǽ sœ́can woldǽ,
mérnǽ þéodæn, þá him wæs monná þearƀ.
þonǽ síþ-fæt him snotrǽ ceorlas
lýt-hwón lógun, þéh hé him léoƀ wérǽ:
hwettun hygi-rófnǽ hǽl scéawadun.
hæƀdǽ se gódá Géatá líodá
cæmpan gicoronǽ, þárá-þe hé cœ́nustǽ
findan mæhtǽ. Fífténá sum
sund-wudu sóhtǽ: secg wísadǽ,
lægu-cræftig mon, lond-gimercu.
(Ýðlád)
First forþ giwát. Flotá wæs on ýðum,
bát undær bærgǽ. Beornas gearwǽ
on stefn stigun. Stréamas wundun,
sund wiþ sondǽ. Secgas bérun
on bearm nacan berhtǽ frætwǽ,
gúð-searu geatulíc. Guman út scuƀon,
weras on wil-síþ, wudu bundænnǽ.
Giwát þá oƀær wég-holm, windǽ gifýsid,
flotá fámig-hals, fuglǽ gilícust,
oþþæt ymb án-tíd, óðræs dógræs
wundæn-stefná giwædæn hæƀdǽ,
þæt þá líðændí lond giségun,
brim-cliƀu blícan, bergas stéapǽ,
sídǽ sǽ-nǽssas. Þá wæs sund lidæn,
eoletæs(?) æt ændí. Þanon ŭ́p hraðǽ
Wedrá líodí on wong stigun:
sǽ-wudu sǽldun, serċan hrisidun,
gúð-giwédu. Godǽ þoncadun,
þæs-þe him ýð-ládǽ éðí wurdun...