'The [Danish] host marched across Northumbria and East Anglia so that the [Saxon] levies were unable to get at them, until they reached east Essex, on an island out at sea called Mersea (hie comon on Eastseaxna lond easteweard on an igland paet is ute on paere sae, paet is Meresig haten)

... Then the same year before winter the Danish who occupied Mersea pulled their ships up Thames and then up the Lea. That was two years after they had come hither oversea.'

c 951-959: Will of Ealdorman Aelfgar Aelfgar granted his estates at Peldon and Mersea to his family's monastery of 'Stoke', although his elder daughter, Aethelflaed of Damerham, widow of King Edmund, could have the use of the estates during her lifetime. Another estate, at Totham, was granted to his younger daughter, Aelfflaed, and her husband Byrhtnoth, and after their death 'is to go to Mersea for my daughter Aethelflaed.' Concluding his will, Aelfgar appealed to whoever was then king to guarantee the operation of his will, praying that anyone who altered the will: 'may never repent it except in the torment of hell, unless I myself alter it before my death.'

Before 991: Will of Aethelflaed of Damerham According to the records of Ely Abbey, 'she seemed to be the noblest of her kinsfolk. However, while she seemed to cling to the uncertain riches of this world, she was devoutly scrupulous about the observance of holy religion.' As well as bequests to the then king, comprising estates, four gold armlets, four robes, four cups, four bowls and four horses, Aethelflaed left estates to the abbeys of Glastonbury, Canterbury, Ely and Bedericesworth [Bury St Edmunds]. She also remembered the smaller minster on her estate at Mersea: 'And I grant the estate at Fingringhoe to the Ealdorman Brihtnoth and my sister for her life; and after her death to St Peter's church at Mersea ... And I grant the estates at Peldon and at Mersea and at Greenstead to Stoke after my death, and after the death of the Ealdorman Brihtnoth and my sister.'

Before 995: Will of Aethelric of Bocking

On the morning after Aethelric's marriage, he gave his new wife, Leofwine, the traditional 'morning-gift': two hides of land on Mersea Island. Some years later, Aethelric and Leofwine put their names to a charter bequeathing land at Bocking and Mersea to 'the church of the Holy Saviour in Dorobernia', [Christ Church, Canterbury]. Aethelric's will repeats the bequest of his Bocking estate (except for one hide to the local priest) to Christ Church, Canterbury, to be paid after his wife's death, 'for our souls and for that of my father who obtained it'. Aethelric's widow, Leofwine, promised that, in addition to her husband's bequest of Bocking to Christ Church, Canterbury, she would also give the same church her 'morning-gift': the two hides of land on Mersea Island.

1000-1002: Will of Aelfflaed, widow of Ealdorman Byrhtnoth

AElfflaed's will, dated c. 1002, confirmed the bequest of Peldon and Mersea to Stoke, and noted that her father had presented a wood at Totham to the minster at Mersea, which possessed also the whole of the six hides of land forming the western half of the island.  The Liber Eliensis records that Aelfflaed gave to Ely Abbey a tapestry or hanging celebrating the heroic deeds of Byrthtnoth, who was buried there after his death at the battle of Maldon.

Note
A hide is 120 acres

More Mersea history.