The Supply Depot is a building in Napoleon: Total War.
A supply depot allows an army to march very efficiently, and will be in a condition to fight after they have marched.
Good generals understand that fighting battles is only a small part of military affairs. Equally important to success is in keeping an army healthy, supplied, and capable. To do this requires organisation and, above all, a good supply corps: a soldier without ammunition might as well have stayed at home as come to the battlefield.
Part of Napoleon's genius for military affairs lay in his ability to take existing systems and make them work at full efficiency. His armies simply could not have functioned without a supply system, even though French armies were also much given to plundering, looting, and terrible depredations on foreign civil populations, all in the name of foraging. Stripping a country of everything might feed the men, but it could not provide the purely military supplies that they required: ammunition, powder, and uniforms, even boots. Huge stocks of matériel were required for any army, even one that did not fight, as life in the field wore out everything! Foraging only worked n relatively prosperous lands: one of the reasons that the invasion of Russia ended in disaster was that the Russians themselves destroyed everything in the French path, rather than let them have it.
- +1% to replenishment rates in all your regions
- +22% to the replenishment rate in this region
The Supply Depot provides the single largest increase to replenishment rate of any building in the game. Its effects stack with those of other replenishment buildings such as farms, technologies and roads. Huge as this bonus is, it is often redundant in the late game due to the prevalence of said farms, technologies and roads already providing a large replenishment rate by themselves. Supply depots are unusual compared to their predecessors in that they provide a global replenishment rate increase, meaning that even supply depots in regions far from combat serve a (minimal) purpose. The only other building which grants a similar bonus is the Minin Monument, available only to Russia.
The Supply Depot competes for the same building slot as the Banking House, a building that generates large amounts of money but has no direct military benefits. As building one precludes the other, Supply Depots are best built in areas that are near fighting, while their relative lack of use makes them prime candidates for conversion to banking houses in regions far from conflict. Damaging enemy supply depots through sabotage or raiding can be an effective strategy. As with most final-tier buildings, supply depots require a technology before they can be built. Once they are built, they may only be converted to banking houses if Joint Stock Company has been researched. The only way to switch supply depots to the economic branch of buildings without this technology researched is to destroy them and then build Markets from scratch.