Veterancy is a quality of the units of Company of Heroes. When a unit receives enough experience, its Veterancy level improves. Veterancy bestows permanent bonuses to the unit, improving its combat performance in one or more ways.
Different factions have different methods of obtaining veterancy, and their units benefit differently from each Veterancy level. In fact, most unit types get different bonuses from other units types in their own army!
Consult the specific articles below to see how each faction handles Veterancy for its units.
American[]
The American army uses a simple and straightforward Veterancy system that is treated as the basis for comparison with all other systems.
American units gain experience points by killing enemy units in combat. Once a sufficient number of these points is accumulated, the unit will rise in Veterancy.
Each American unit gains different bonuses from Veterancy. These bonuses are specifically tailored to the combat requirements for that unit.
As a result of this system, American units that have remained alive during several battles will become stronger and better at what they do. This is why the Americans are best advised to keep their units alive, withdraw damaged units for repairs/reinforcement, and seek combat whenever possible to train their units up.
Wehrmacht[]
Wehrmacht units do not accumulate experience points. To achieve higher Veterancy levels, specific upgrades must be purchased at the Kampfkraft Center.
Once an upgrade is purchased, it will raise the Veterancy level of all units from several specific unit types. Both existing and future units are affected - so newly produced units will already have as much Veterancy as existing ones.
There are four upgrades to be purchased, with each upgrade improving one set of units - for example, an Infantry Veterancy upgrade, a Tank Veterancy upgrade, and so forth. Each upgrade has 3 levels, each corresponding with one of the three Veterancy levels. Therefore, purchasing the first infantry upgrade will raise all infantry units to Veterancy level 1, the second upgrade will raise them to level 2, and the third to level 3.
As a result, by the later stages of the game the Wehrmacht's base structures will be producing high-veterancy units. For this reason the loss of a veteran Wehrmacht unit is less important than it is for other factions.
Panzer Elite[]
The Panzer Elite's Veterancy system allows the player to choose whether a unit should specialize in defensive or offensive actions.
Panzer Elite units gain experience points during battle, and many units will also share experience points with other nearby Panzer Elite units. Thus, groups of units will gain experience together, and even unarmed units will eventually go up in Veterancy.
Each time a unit "levels up", the player is given a choice between giving this unit a Defensive bonus (usually extra speed, hit points and other defensive qualities) or an Offensive bonus (usually penetration, faster firing rate, higher accuracy, and so on). A single unit can pick any combination of these as it levels up, so it could end up with a mix of defensive and offensive bonuses by Veterancy level 3, or simply have all defensive or all offensive bonuses. This "tailors" a unit to a more specific role on the battlefield.
All infantry receive the same bonuses when leveling up. Similarly, all vehicles receive the same bonuses when leveling up. The bonuses are not tailors to each unit type, as they are in the American and Wehrmacht armies.
British[]
Most British units do not gain experience at all, nor do they go up in Veterancy levels. There are only three units that do so - the Lieutenant, Captain, and the optional Cromwell Command Tank.
These units themselves confer veterancy-like bonuses to similar units in their vicinity. For example, the presence of a nearby Lieutenant makes British infantry units stronger. The higher the Lieutenant's level, the better the bonuses he bestows to his nearby mates.
This puts high emphasis on keeping these "command units" alive during combat, which can be difficult due to the fact that they are very lightly armed. Fortunately, experience gained by nearby units is instantly transferred to any nearby "command unit", so these units do not usually have to risk themselves too much in order to go up in level.
Company of Heroes 2[]
In Company of Heroes 2, Veterancy is streamlined to follow the American Veterancy system from Company of Heroes 1. All factions units will gain experience from combat to allow for an increase in veterancy when enough experience is accrued. Units have different veterancy requirements relative to their cost, and also gain experience from causing damage relative to their target's cost (which tends to means doing anti-tank damage with basic infantry will give the infantry a sizeable chunk of experience at once even if they don't kill the tank) in addition to scoring kills. Different units will have different bonuses that they gain and will also gain different abilities for said units. Because Veterancy does not "transfer", it is essential for veteran units to be kept alive at all costs.
The Soviets, Ostheer, British and American factions have 3 stars veterancy for all their units. The only faction that does not follow this formula is the Oberkommando West, which have a whopping 5 stars veterancy for its units. The Ostheer does have a unit that can be called in with full veterancy, but it does inhibit their resource input.