 It took another hundred years for the defences on Gravesend Reach to be improved, in the form of new works at Gravesend and Tilbury built in the 1780s, but even then the potential of forward defence – to prevent enemies accessing the lower Thames – continued to be neglected.It was not until the outbreak of the French Revolutionary Wars that the need for effective forward defence was addressed.Lieutenant Colonel Hartcup of the Royal Engineers carried out a survey of the Thames in 1794 in which he recommended building a triangle of artillery batteries to guard the entrance to Gravesend Reach and the next reach of the river, Lower Hope Reach.