Question: What treaty has a document not specifically linked to Wedmore that is a Treaty of Alfred and Guthrum, that was the result of an army of the Anglo-Saxon kingdom of Wessex under Alfred the Great defeating the Great Heathen Army?

Context paragraphs:
Bury St Edmunds Abbey: The Abbey of Bury St Edmunds was once among the richest Benedictine monasteries in England, until the Dissolution of the monasteries in 1539.  It is in the town that grew up around it, Bury St Edmunds in the county of Suffolk, England.  It was a centre of pilgrimage as the burial place of the Anglo-Saxon martyr-king Saint Edmund, killed by the Great Heathen Army of Danes in 869.  The ruins of the abbey church and most other buildings are merely rubble cores, but two very large medieval gatehouses survive, as well as two secondary medieval churches built within the abbey complex.

Great Heathen Army: The Great Viking Army or Great Danish Army, known by the Anglo-Saxons as the Great Heathen Army (OE: "mycel hæþen here"), was a coalition of Norse warriors, originating from Denmark (and likely also from Sweden and Norway) who came together under a unified command to invade the four Anglo-Saxon kingdoms that constituted England in AD 865.

Treaty of Alfred and Guthrum: The Treaty of Alfred and Guthrum is an agreement between Alfred of Wessex and Guthrum, the Viking ruler of East Anglia.  Its date is uncertain, but must have been between 878 and 890.  The treaty is one of the few existing documents of Alfred's reign; it survives in Old English in Corpus Christi College Cambridge Manuscript 383, and in a Latin compilation known as "Quadripartitus".  All translations below come from Dorothy Whitelock, "English Historical Documents 500-1042".

Ohthere of Hålogaland: Ohthere of Hålogaland (Norwegian: "Ottar fra Hålogaland" ) was a Viking Age Norwegian seafarer known only from an account of his travels that he gave to King Alfred (871–99) of the Anglo-Saxon kingdom of Wessex in about 890 AD.  His account was incorporated into an Anglo-Saxon, or Old English, version of a Latin historical book written early in the 5th century by Paulus Orosius, called "Historiarum Adversum Paganos Libri VII", or "Seven Books of History Against the Pagans".  The Old English version of this book is believed to have been written in Wessex in King Alfred's lifetime or soon after his death, and the earliest surviving copy is attributed to the same place and time.

Æthelflæd: Æthelflæd, Lady of the Mercians ( 870 - 12 June 918) ruled Mercia in the English Midlands from 911 until her death.  She was the eldest daughter of Alfred the Great, king of the Anglo-Saxon kingdom of Wessex, and his wife Ealhswith.  Æthelflæd was born around 870 at the height of the Viking invasions of England.  By 878 most of England was under Danish Viking rule, East Anglia and Northumbria having been conquered and Mercia partitioned between the English and the Vikings, but in that year Alfred won a crucial victory at the Battle of Edington.  Soon afterwards the English-controlled western half of Mercia came under the rule of Æthelred, Lord of the Mercians, who accepted Alfred's overlordship.  Alfred adopted the title King of the English, claiming to rule all English people not living in areas under Viking control.  In the mid-880s, Alfred sealed the strategic alliance between the surviving English kingdoms by marrying Æthelflæd to Æthelred.

Battle of Edington: At the Battle of Edington an army of the Anglo-Saxon kingdom of Wessex under Alfred the Great defeated the Great Heathen Army led by Guthrum on a date between 6 and 12 May AD 878, soon resulting in the Treaty of Wedmore later the same year.  The primary sources locate the battle at ""Ethandun"" or ""Ethandune"", and until a scholarly consensus identified its location with the present-day Edington in Wiltshire it was known as the Battle of "Ethandun", a name which continues to be used.

Treaty of Wedmore: The Peace of Wedmore is a term used by historians for an event referred to by the monk Asser in his Life of Alfred, outlining how in 878 the Viking leader Guthrum was baptised and accepted Alfred as his adoptive father.  Guthrum agreed to leave Wessex and a "Treaty of Wedmore" (sometimes called the "Treaty of Chippenham") is often assumed by historians to have existed.  No such treaty still exists.  However, there is a document not specifically linked to Wedmore that is a Treaty of Alfred and Guthrum.

Battle of Lüneburg Heath: The Battle of Lüneburg Heath (also called the Battle of Ebstorf) was a conflict between the army of King Louis III of France and the Norse Great Heathen Army fought on 2 February 880 AD, at Lüneburg Heath in today's Lower Saxony.

Repton Abbey: Repton Abbey was an Anglo-Saxon Benedictine abbey in Derbyshire, England.  Founded in the 7th century, the abbey was a double monastery, a community of both monks and nuns.  The abbey is noted for its connections to various saints and Mercian royalty; two of the thirty-seven Mercian Kings were buried within the abbey's crypt.  The abbey was abandoned in 873, when Repton was overrun by the invading Great Heathen Army.

Halfdan Ragnarsson: Halfdan Ragnarsson (Old Norse: "Hálfdan" ; or "Healfdene"; Old Irish: "Albann" ; died 877) was a Viking leader and a commander of the Great Heathen Army which invaded the Anglo-Saxon kingdoms of England, starting in 865.  According to the tradition recorded in the Norse sagas he was one of the sons of Ragnar Lodbrok, and his brothers included Björn Ironside, Ivar the Boneless, Sigurd Snake-in-the-Eye and Ubba.  He was the first Viking King of Northumbria and a pretender to the throne of Kingdom of Dublin.  He died at the Battle of Strangford Lough in 877 trying to press his Irish claim.

Supporting paragraphs: Battle of Edington Treaty of Wedmore
Answer: Treaty of Wedmore