 Noting the importance of the Thames and its vulnerability to seaborne attack, the Commission advocated in its report in 1860 that two principal lines of defence should be established along the Thames.Three forts would be constructed or rebuilt - Shornemead Fort and Cliffe Fort in Kent and Coalhouse Fort in Essex - to provide an outer line of defence, with further forts and batteries protecting key sites further downriver.The inner line of defence would be provided by Tilbury Fort and New Tavern Fort.