Original sentence: The violent storms of later centuries (particularly the 13th) were to cut the town off from the sea; and, when the River Rother (which had by now changed its course) and the sea combined in about 1375 to destroy the eastern part of the town, ships began use the current area (the Strand) to off-load their cargoes
Edited sentence: The violent storms of later centuries (particularly the 13th) were to cut the town off from the sea; and, when the River Rother (Eastern) (which had by now changed its course) and the sea combined in about 1375 to destroy the eastern part of the town, ships began use the current area (the Strand) to off-load their cargoes