Attrition is a gameplay mechanic in the Total War series. Armies faced with attrition gradually lose men over time, described as losses due to desertion, starvation, and exposure. Attrition first appears in Napoleon: Total War; units in earlier games could travel in any terrain, friendly or otherwise, and not sustain losses.
Napoleon: Total War[]
Attrition makes its first appearance in Napoleon: Total War. Armies with flags flashing red on the campaign map (only a factor in the Egypt Campaign) are suffering from heat attrition, while armies with flashing blue flags are suffering from cold attrition. When under the effects of attrition, units do not benefit from the effects of replenishment whatsoever--even in towns filled with Supply Posts, roads and farms.
Armies stationed in towns are immune to the effects of attrition. Units that are heat or cold resistant are also immune, as are generals and most elite units. All Russian units are immune to cold attrition, and nearly all Ottoman units are immune to heat attrition. The Crimean Khanate has one unit that is immune to cold attrition.
The effects of attrition set in at the end of the turn cycle (so, for example, a full-strength army marching into an area of attrition and is attacked at any point during the other factions' turn cycles remains at full strength, and attrition only sets in after the other factions have finished their turn).
Cold attrition only occurs during winter months (late November to late February). While areas of attrition are present throughout some parts of the world map, it is by far the most prevalent in Eastern Europe and Russia, where practically entire regions are areas of attrition--with towns few and far between to shelter armies from the environment. This gives Russia a very powerful home field advantage in the winter. Analogously, most Ottoman troops have a stamina and attrition advantage over their French foes in Egypt. Unfortunately for the Ottoman Empire, there are no regions affected by heat attrition in the Europe campaign.
Total War: Shogun 2[]
Attrition returns in Total War: Shogun 2, with nearly all of the world map becoming areas of attrition during the winter. Unlike Napoleon, attrition does not affect units in friendly or neutral territory. As units may no longer be stationed in towns, they cannot avoid attrition by ending a turn in one.
Attrition is more sporadic than in Napoleon, as each turn is three months instead of two weeks; attrition thus lasts for one turn every four turns, meaning that armies only suffer minimal attrition unless spending unusually long amounts of time in hostile territory.
Fall of the Samurai[]
Attrition in Fall of the Samurai is nearly identical mechanically to its appearance in Shogun 2, with a few important differences: each turn is two weeks instead of three months, making attrition last far longer than Shogun 2. This, compared with the larger map, poorer movement rate of units, and slower replenishment rate, can make assaulting provinces in the winter a daunting prospect if not done quickly: units could face up to six turns of attrition in a row compared to one from ''Shogun 2''. Using geisha or especially shinobi to trap armies can cause their numbers to quickly plummet. To alleviate this, railway systems in the late game can quickly transport troops through areas of attrition to their objectives.
Total War: Three Kingdoms[]
Attrition is a negative effect suffered by armies that causes damage over time to its units and reduces its unit morale should a battle ensue while the effect is active. The main factor that causes attrition is low military supplies. This can be remedied by returning the army to your own or allied territory where reserves are present, at which point it will automatically begin to resupply. Attrition is indicated by the shadows of soldiers falling away from the army on the campaign map.