Question: What did the Anglo-Saxons fail to prevent during the battle which inspired the J.R.R. Tolkien work The Homecoming of Beorhtnoth Beorhthelm's Son?

Context paragraphs:
The Homecoming of Beorhtnoth Beorhthelm's Son: The Homecoming of Beorhtnoth Beorhthelm's Son is the title of a work by J. R. R. Tolkien that was originally published in 1953 in volume 6 of the scholarly journal "Essays and Studies by Members of the English Association", and later republished in 1966 in "The Tolkien Reader".  It is a work of historical fiction, inspired by the Old English poem "The Battle of Maldon".  It is written in the form of an alliterative poem, but is also a play, being mainly a dialogue between two characters in the aftermath of the Battle of Maldon.  The work was accompanied by two essays, also by Tolkien, one before and one after the main work.

Túrin Turambar: Túrin Turambar (pronounced ) is a fictional character in J. R. R. Tolkien's legendarium. " "Turambar and the Foalókë"", begun in 1917, is the first appearance of Túrin in the legendarium.  J.R.R. Tolkien consciously based the story on the medieval tale of Kullervo in the Finnish mythological poem "Kalevala", saying that it was "an attempt to reorganize...the tale of Kullervo the hapless, into a form of my own".  Also called ""The Tale of Grief"", ""Narn i Chîn Húrin"", commonly called "The Narn", it tells of the tragic fates of the children of Húrin, namely his son Túrin (Turambar) and his daughter Nienor.  Excerpts of the story were published before, in "The Silmarillion" (prose), "Unfinished Tales" (prose), "The Book of Lost Tales" Part II (prose), "The Lays of Beleriand" (verse in alliterative long-lines) and most recently in 1994 in "The War of the Jewels" (prose), the latter three part of "The History of Middle-earth" series.

Sellic Spell: Sellic Spell (] , an Old English phrase meaning "wondrous tale" and taken from the poem "Beowulf") is a short prose text available in Modern and Old English redactions, written by J.R.R. Tolkien in a creative attempt to reconstruct the folktale underlying the narrative in the first two thousand lines of the Old English poem "Beowulf".  Among other things, it seeks to clarify and integrate a number of narrative strands in the Anglo-Saxon poem.  The resulting text is a loose variant of the "Skilful Companions" type of folktale, in which each of several characters (two or three in Tolkien's text, depending on the redaction) has a valuable but specific skill.  Unlike in folktales of that type, however, the skills of Tolkien's characters do not supplement each other in the resolution of the narrative problem.  Tolkien's recasting of the material also incorporates the sluggish youth motif and the abandonment of the hero at the waterfall, both elements found in the analogous Old Icelandic "Grettis saga".  The suggestion that a waterfall like that of "Grettis saga" was part of the original setting of the pool of monsters in "Beowulf" was made by W.W. Lawrence in 1912.

J. R. R. Tolkien: Author of the Century: J.R.R. Tolkien: Author of the Century is a work of literary criticism written by Tom Shippey.  It is about the work of J.R.R. Tolkien.  In it, Shippey argues for the relevance of Tolkien today and attempts to firmly establish Tolkien's literary merits.

The Battle of Maldon: The Battle of Maldon is the name given to an Old English poem of uncertain date celebrating the real Battle of Maldon of 991, at which the Anglo-Saxons failed to prevent a Viking invasion.  Only 325 lines of the poem are extant; both the beginning and the ending are lost.

The Lord of the Rings (soundtrack): The J.R.R. Tolkien's The Lord of the Rings OST is the soundtrack to Ralph Bakshi's animated film adaptation of J.R.R. Tolkien's "The Lord of the Rings", featuring music composed by Leonard Rosenman.  It was issued as a double-LP in 1978.  In 2001, the album was reissued on CD, with bonus tracks.  The album reached #33 in the Canadian RPM Magazine album charts, February 24, 1979.

Arden R. Smith: Arden Ray Smith (January 4, 1966) is a member of the Elvish Linguistic Fellowship and holds a Ph.D. in Germanic Linguistics from the University of California, Berkeley.  He has published numerous articles relating to the invented languages of J.R.R. Tolkien.  He was a columnist and editor of "Vinyar Tengwar", for which he wrote the popular column "Transitions in Translations", in which odd elements in translations of Tolkien's work were described and commented upon.

Tolkienmoot: Tolkienmoot (also advertised as Tolkien Moot and TolkienMoot (camel case)) originally began under the name of Merpcon in 2005.  Always a convention focused on J.R.R. Tolkien and gaming in Middle-earth, as the venue expanded to include a broader array of game systems, guest speakers, and special events, it was decided to change the title to Tolkienmoot in 2009.  The convention was founded, and continuous to be funded and run by Hawke Robinson, founder of the Inland Empire Eä Tolkien Society an official Smial of the U.K. Tolkien Society, RPG Research, Other Minds Magazine, Middle-earth Radio, Middle-earth Talk, Eä RPG, and other endeavours, as well as an active member of CAR-PGa (Committee for the Advancement of Role-Playing Games website), WSTRA (Washington State Therapeutic Recreation Association website), and others.

Eru Ilúvatar: Eru Ilúvatar is a fictional character in J.R.R. Tolkien's Middle-earth legendarium.  He is introduced in "The Silmarillion" as the supreme being of the universe, creator of all existence.  In Tolkien's invented Elvish language Quenya, "Eru" means "The One", or "He that is Alone" and "Ilúvatar" signifies "Father of All".  The names appear in Tolkien's work both in isolation and paired ("Eru Ilúvatar").

Corey Olsen: Corey Olsen is a professor and podcaster known as the Tolkien Professor best known for his work in new media promoting the works of J.R.R. Tolkien and Anglo Saxon literature.  Formerly a professor at Washington College, Olsen now dedicates his time to Signum University, an online learning facility he founded in 2012.

Supporting paragraphs: The Homecoming of Beorhtnoth Beorhthelm's Son The Battle of Maldon
Answer: Viking invasion