Penn, 1800 (Penn, Buckinghamshire, England, UK) 51°37'52"N 00°40'36"W

Explanatory text to a plan of the camp at Homer Green, March 1800. French Revolutionary Wars (1792-1802).

Although the authorship of this 'Explanation' has been ascribed to Thomas Birch, the watermark of 1815 shows that it could not have been written before that date. Birch was appointed Major-General on 4 June 1814. He may have had the map in his possession at that time, writing this explanation before presenting it to George III. Birch was one of the early 'Wycombites' – pupils at the Royal Military College at High Wycombe – who were praised during the Peninsular War as being 'of infinite use' and whose maps and plans were drawn 'in a style of perfection that does them great credit'.

Homer Green is an area south-east of Penn and is shown on the map at RCIN 735083.1.b. The conventional signs for routes passable to all troops, passable only to infantry, and impassable, which are explained in this text are to be found on that map. Also explained is the principle of relative command: 'The Number on the Summits / of the heights [shown on the map] denote their / relative command, increasing / as the Numbers increase.

For an account of the use of relative command in British military mapping see Jones (1974).

Condition: one fold line.