The Second World War stop line between Hoo St Werburgh and Higham Marshes is a notable surviving example of anti-invasion defence. It is the northern section of the Newhaven-Hoo General Headquarters (GHQ) Line where it crosses the Hoo Peninsula in Kent between the rivers Medway and Thames. It is an important remnant of the Second World War defended landscape of the peninsula and is a well-preserved example of this type of defence, which is part of a major chapter in the national story. The surviving remains form a coherent pattern of defence linked to the local topography and connect our perceptions of the current landscape with the fear of invasion experienced by a previous generation. The line was part of a national network of defences and was constructed in July and August 1940 to hinder invading forces from the Kent and Sussex coast. The defensive line used natural and manmade obstacles connected by sections of anti-tank ditch. The line was heavily defended and included pillboxes, anti-tank gun emplacements and road blocks. The surviving parts of the stop line, including buried and surface remains of the anti-tank ditch, provide a coherent and legible picture of how these defences were intended to work. The stop line was identified for further work during the English Heritage Hoo Peninsula Historic Landscape Project. This report describes the elements that make up the line on the Hoo Peninsula, recorded principally from 1940s aerial photographs, and includes an assessment of current survival from recent aerial photographs and field visits.