Experience

Experience (short: **XP**) is primarily gained by units in combat and allows you to promote them, making them stronger and specializing them.

## Uses

The primary use of experience is to gain promotions for your units. When a unit has earned enough experience to choose a promotion, the game will ask you to do so. The promotion needs to be chosen immediately unless the "Allow Promotion Saving" option was checked when starting the game. However, it is possible to delay choosing a promotion by attacking with the unit in question - after attacking you can't choose the promotion, but will be asked to do so in the next turn. The promotions that can be chosen for a unit depend on the promotions that unit already has, and on its combat type (see the page on promotions for details).

The amount of experience needed for the next promotion is 10\*n to choose the n-th promotion. This applies on Standard speed, promotions on Epic Speed need 150% of that amount, on Marathon 300% and on Quick 67%. Take note that the table below shows the total experience needed while 10\*n is the experience needed between two promotions.

Furthermore, the XP gained from combat of all units combined is responsible for the appearance of Great Generals (land and air combat) and Great Admirals (naval combat). Percentage modifiers such as "50% more experience from combat" do not influence the number of Great General points earned, the same as non-combat sources of XP doesn't contribute. Also, combat against Barbarians doesn't grant Great General points unless the option "Barbarian GG/GA points" is checked at the beginning of the game.

## Sources of Experience

A unit can gain experience by various ways. First, all actions performed in combat give XP:

* Performing a melee (naval or land) attack gives 5 XP.
* Performing a ranged (naval or land) attack gives 2 XP.
* Defending against a melee (naval or land) attack gives 4 XP.
* Defending against a ranged (naval or land) attack gives 2 XP.
* Performing an air strike gives 4 XP.
* Defending against an air strike gives 2 XP.

However, the amount of XP gained from Barbarians is limited: Once a unit has more 45 XP, no further XP is earned in combat against barbarian units.

Furthermore, some buildings and wonders give XP to units created in a city. Units built or bought with faith gain the whole experience, while units bought with gold gain only half of it (rounded down).

* Barracks give 15 XP.
* The Armory gives 20 XP.
* The Military Academy gives 25 XP.
* The religious building Order (unlocked via the corresponding Follower belief) gives 15 XP to all land units created in a city.
* The world wonder Brandenburg Gate gives 15 XP.

Some civilizations also have access to unique buildings providing XP:

* The Assyrian National Wonder Royal Library grants 5 XP per Great Work of Writing to all units created in any city, up to a maximum of 45 XP.
* The Japanese Dojo (an Armory replacement) gives 25 XP to all units created in a city.
* The Polish Ducal Stable (a Stable replacement) gives 15 XP to all Mounted Melee Units created in a city.
* The Zulu Ikanda (a Barracks replacement) gives 15 XP to all units created in a city.

Other direct sources of XP are the following:

* Units with the Reconaissance promotion have a 20% chance of gaining 1 XP when revealing a tile. These are the units of the explorer line (Pathfinder, Scout, Explorer and its Brazilian replacement Bandeirantes, Zeppelin) and the Carthaginian Quinquereme.
* The City State Quest "Conquer a city" grants XP to all existing units when completed.
* The Autocracy tenet "Elite Forces" grants 15 XP to all newly created units.
* The Swedish unique ability "Lion of the North" grants 15 XP to all existing units whenever a Great General is born.
* The Portuguese Nau gains XP when using the "Exotic Cargo" ability.

In addition to that, other things can modify the amount of XP gained:

* The Freedom tenet "Draft Registration" eliminates the XP penalty for units bought with gold.
* The Order tenet "Guerilla Warfare" increases the XP gained from combat in friendly lands by 50%.
* The Autocracy tenet "Elite Forces" increases the XP gained from combat by 50%.
* The strategic Oil monopoly adds 5 XP to units after each combat.
* Zulu units don't get more XP from combat, but need 25% less experience for promotions.
* The Japanese Samurai gains 50% more XP from combat due to the Quick Study promotion.
* Units with the Sincerity promotion gain 50% more XP from combat. This promotion can only be obtained randomly after the first fight of a unit with the "Eight Virtues of Bushido" promotion granted by the Japanese Dojo.