A Second World War anti-invasion Defence Area was established at Sarre during 1940/41. This was part of the national response against a possible German invasion following the defeat of the British Expeditionary Force in France in 1940.

Sarre village formed the focus of the Defence Area. In 1940, the village was categorised as a Category A nodal point in number 7 Sector, 43 Division, Eastern Command. Brigade Headquarters for troops tasked with defending the area was established at Sarre and between July and August 1940, B Company of 1st Canadian Pioneer Battalion prepared Sarre for all-round defence. The work included fortifying buildings in the village as well as building pillboxes and roadblocks and mining structures such as bridges.

The degree of survival of military features in the village as at the early 2000s is described by William Foot in 'Defence Areas. A National Study of Second World War Anti-Invasion Landscapes in England' and is not repeated here. Further elements of the defence system inluding extensive barbed wire entanglements on the marshes to the south-west of the village were identified by the Historic England Isle of Thanet project (2024). (1)

<1> English Heritage, 2004, Defence areas: a national study of Second World War anti-invasion landscapes in England (Unpublished document). SKE17661.