In the latter half of the 19th century, growing public concern over the ability of the British armed forces to repel an invasion (stoked, in part, by the serialisation of George Tomkyns Chesney's 1871 novella The Battle of Dorking), prompted the government to announce the construction of thirteen fortified mobilisation centres, collectively known as the London Defence Positions. Two centres were built on Box Hill, approximately apart: one close to the present National Trust visitor centre (commonly called Box Hill Fort) and the other close to the summit of the hill, to the south of the present day Box Hill village (known as Betchworth Fort).