 The rapid development of artillery weapons in the late 19th century meant that the casemate style of fortification had become virtually obsolete within a decade of the fort's completion.Its original purpose of defending the river against large warships was taken over by a new East Tilbury Battery, constructed in 1891 about to the north-west just outside East Tilbury village.This contained six much more powerful breech-loading (BL) guns on Moncrieff disappearing carriages within concealed emplacements facing east up the river.