However, in his time it was usual to print each half-line as a separate line on the page. For the comfort of people used to seeing both half-lines together, I've taken that liberty below. I've kept the capitalization the same as Tennyson had it, even though I've joined the half-lines.
Constantinus, King of the Scots, after having sworn allegiance to Athelstan, allied himself with the Danes of Ireland under Anlaf, and invading England, was defeated by Athelstan and his brother Edmund with great slaughter at Brunanburh in the year 937.
Athelstan King, Lord among Earls,Bracelet-bestower and Baron of Barons,He with his brother, Edmund Atheling,Gaining a lifelong Glory in battle,Slew with the sword-edgeThere by Brunanburh, Brake the shield-wall,Hew'd the lindenwood, Hack'd the battleshield,Sons of Edward with hammer'd brands.Theirs was a greatness Got from their Grandsires--Theirs that so often in Strife with their enemiesStruck for their hoards and their hearths and their homes.Bow'd the spoiler, Bent the Scotsman,Fell the shipcrews Doom'd to the death.All the field with blood of the fightersFlow'd, from when first the greatSun-star of morningtide,Lamp of the Lord God Lord everlasting,Glode over earth till the glorious creatureSank to his setting.There lay many a man Marr'd by the javelin,Men of the Northland Shot over shield.There was the Scotsman Weary of war.
We the West-Saxons,
Long as the daylight Lasted, in companiesTroubled the track of the host that we hated;Grimly with swords that were sharp from the grindstoneFiercely we hack'd at the flyers before us.Mighty the Mercian, Hard was his hand-play,Sparing not any of Those that with Anlaf,Warriors over the Weltering watersBorne in the bark's-bosom,Drew to this island: Doom'd to the death.Five young kings put asleep by the sword-stroke,Seven strong earls of the army of AnlafFell on the war-field, numberless numbers,Shipmen and Scotsmen.
Then the Norse leader, Dire was his need of it,
Few were his following, Fled to his warship;Fleeted his vessel to sea with the king in it,Saving his life on the fallow flood.Also the crafty one, Constantinus,Crept to his north again, Hoar-headed hero!Slender warrant had He to be proud ofThe welcome of war-knives--He that was reft of hisFolk and his friends that had Fallen in conflict,Leaving his son too Lost in the carnage,Mangled to morsels, A youngster in war!Slender reason had He to be glad ofThe clash of the war-glaive--Traitor and trickster And spurner of treaties--He nor had Anlaf With armies so brokenA reason for bragging That they had the betterIn perils of battle On places of slaughter--The struggle of standards,The rush of the javelins,The crash of the charges,The wielding of weapons--The play that they play'd withThe children of Edward.Then with their nail'd prows Parted the Norsemen, aBlood-redden'd relic ofJavelins over The jarring breaker, the deep-sea billow,Shaping their way toward Dyflen again, Shamed in their souls.
Also the brethren, King and Atheling,
Each in his glory,Went to his own in his own West-Saxonland,Glad of the war.Many a carcase they left to be carrion,Many a livid one, many a sallow-skin--Left for the white-tail'd eagle to tear it, andLeft for the horny-nibb'd raven to rend it, andGave to the garbaging war-hawk to gorge it, andThat gray beast, the wolf of the weald.Never had huger Slaughter of heroesSlain by the sword-edge--Such as old writersHave writ of in histories--Hapt in this isle, sinceUp from the East hither Saxon and Angle fromOver the broad billow Broke into Britain withHaughty war-workers who Harried the Welshman, whenEarls that were lured by theHunger of glory gat Hold of the land.