Napoleon's military successes were due to a large degree to the efficiency of his command and control systems or 'headquarters'. These comprised the Great Imperial Headquarters and the Small Imperial Headquarters, both staffed by members of the Military Household and the Civil Household including officers and men of many different departments. This book shows how their functions slotted together into a system that provided the Emperor with all the information he needed to make decisions; with the means to turn those decisions into specific orders, and to distribute them quickly; and with all the protection, logistic and other back-up services that allowed his court to function while on campaign.