MERSEY-ISLAND, (Essex) at the mouth of the Coln, S. of Colchester, was seized on by the Danes, in the R. of K. Alfred, for their winter-quarters. It bel. formerly to the mon. of Christ-church in Canterbury, and was divided into 8 ps. now reduced to 2, viz. East and West-Mersey. The Ch. of the former bel. anciently to the priory of Prittlewell. The manor of Rewsal's in this p. was exchanged with K. Hen. VIII. by Sir Giles Capel, the ancestor of the Es. of Essex, for the Lp. of Stebbing. West-Mersey had an alien priory, to which its manor bel. but K. Hen. V. suppressed the alien priory, and gave it to Abp. Chicheley, who settled it on his collegiate Ch. of Higham-Ferrers. At the Diss. K. Hen. VIII. granted it to R. Dacres, and afterwards to Tho, Ld. Darcy; in whose family it continued, till it passed by marriage to the Savages Es. of Rivers. In its Ch.-yard is a mosaic pavement, supposed to be Othona. The island had a block-house; and in the Dutch war the Pt. put 1000 men in it, to guard it against the Dutch.