An Essay on the Principle of Population
Distinct from earlier, less inclusive censuses (e.g. for religious purposes), national decennial censuses of the general population started in 1801, championed by the statistician John Rickman. The censuses were initially conducted partly to ascertain the number of men able to fight in the Napoleonic Wars, and partly over population concerns stemming from the 1798 work "An Essay on the Principle of Population" by Reverend Thomas Robert Malthus. Rickman's twelve reasons – set out in 1798 and repeated in Parliamentary debates – for conducting a census of Great Britain included the following justifications: