The rivalry between France and Britain in the 1870’s again raised the fear of invasion. To meet such a threat, Colonel Ardagh laid out a defence scheme for the United Kingdom. His key assumption was that an invading enemy’s objective was to be London. His scheme recommended garrisons for the defence of naval bases and commercial ports, a mobile field army concentrated in the south of England and all volunteer troops not required for the defence of ports or naval bases to occupy positions selected for the defence of London. The most likely landing place, where an army would only be a few days march from London, would be between Portsmouth and Harwich; the next best stretch of coast would be between Great Yarmouth to Harwich. Thus, the Field Army, covered by its cavalry and the Imperial Yeomanry, were to be distributed along a front stretching from Aldershot-Gravesend-Colchester. Behind this front, a second line of 10 main positions was to be manned by Volunteers organised in...