In previous civ games, units have only a few levels: conscript, regular, veteran, and elite. Now in Civ4, there are more than 40 promotions you can give to your units as they gain experience, enabling you to customize your units to make them more specialized and more powerful. Some of the promotions give your units a strength bonus, some give your units a bonus against a certain unit type, some make your units better on certain terrain types, while some give your units special abilities such as using enemy roads, faster healing, amphibious attack, and city raider.
In addition, some promotions (like Morale and Leadership) require the use of a Great General, a unit available in Warlords and Beyond the Sword. By joining a Great General to a unit, these promotions become available.
However, not all promotions are available to all units, and the better promotions have other, lesser promotions as prerequisites. The escalating cost of the next promotion ensures that few units will have more than 3-5 promotions, so choose carefully.
Also note that promotions are kept in upgrades, that can lead to upgraded units having promotions that equal but newly built units can’t have. The most notable example ( but by far not the only one ) is the city raider line, that can be present in gunpowder units upgraded from melee units
To add, some promotions, notably Drill II-IV and Guerilla II-III, are available to unit types that cannot take the first promotion in their chain. This is because some Unique Units start with a promotion not usually available to its type – for example, Samurai are Melee units with Drill I, and Gallic Warriors are Melee units with Guerilla I; both units can develop along their paths. Besides that, there are events that give promos to certain units that can’t have them by default, most notably a event that gives combat I to cannons ( in this case you can’t upgrade to combat II though , since the combat line is fully locked for siege unit since BtS 3.13 )
NOTE: Information in this section is correct as of Beyond the Sword v3.17.
| Icon | Promotion | Abilities | Requires | Leads to | Available to |
|---|---|---|---|---|---|
 | Accuracy | +8% City Bombard Damage | City Raider I or Barrage I | – | Siege Weapons |
 | Ace | +25% Evasion Chance | Combat III | – | Air |
 | Ambush | +25% vs. Armored units | Combat II | – | Siege, Gunpowder, Armored, Helicopter, Air |
 | Amphibious | No Combat Penalty for Attacking from Sea; No Combat Penalty Attacking Across River | Combat II | – |
Archery, Mounted, Melee, Siege, Gunpowder |
 | Barrage I | +20 Collateral Damage | – | Barrage II Accuracy | Siege, Armored, Naval |
 | Barrage II | +30 Collateral Damage +10% vs. Melee Units | Barrage I | Barrage III | Siege, Armored, Naval |
 | Barrage III | +50 Collateral Damage +10% vs. Gunpowder Units | Barrage II | – | Siege, Armored, Naval |
 | Blitz | Can Attack multiple Times Per Turn | Combat III and Military Science | – | Mounted, Armored, Helicopter, Naval |
 | Charge | +25% vs. Siege Weapons | Combat I | – | Mounted, Melee, Armored, Helicopter |
 | City Garrison I | +20% city Defense | – | City Garrison II | Archery, Gunpowder |
 | City Garrison II | +25% city Defense | City Garrison I | City Garrison III | Archery, Gunpowder |
 | City Garrison III | +30% city Defense +10% vs. Melee Units | City Garrison II | – | Archery, Gunpowder |
 | City Raider I | +20% City Attack | – | City Raider II, Accuracy | Melee, Siege, Armored |
 | City Raider II | +25% City Attack | City Raider I | City Raider III | Melee, Siege, Armored |
 | City Raider III | +30% City Attack +10% vs. Gunpowder Units | City Raider II | – | Melee, Siege, Armored |
 | Combat I | +10% Strength | – | Combat II Cover Shock Pinch Medic I Charge | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Combat II | +10% Strength | Combat I | Combat III Formation Ambush Amphibious Range I | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Combat III | +10% Strength | Combat II | Combat IV March Blitz Sentry Ace | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Combat IV | +10% Strength Heals Extra 10% Damage/Turn in Neutral Lands | Combat III | Combat V Commando | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Combat V | +10% Strength Heals Extra 10% Damage/Turn in Enemy Lands | Combat IV | Combat VI | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Combat VI | +25% Strength | Combat V and Great General | – | Recon, Archery, Mounted, Melee, Gunpowder, Armored, Helicopter, Naval, Air |
 | Commando | Can Use Enemy Roads and Railroads | Combat IV and Military Science | – | Recon, Artillery, Mounted, Melee, Gunpowder, Armored |
 | Cover | +25% vs. Archery Units | Combat I | – | Archery, Melee, Gunpowder |
 | Drill I | +1 First Strike Chance | – | Drill II, Medic I Cover | Archery, Siege, Armored, Helicopter, Naval |
 | Drill II | +1 First Strike Suffers 20% Less Collateral Damage | Drill I | Drill III | Archery, Siege, Armored, Helicopter, Naval |
 | Drill III | +2 First Strike Chance Suffers 20% Less Collateral Damage | Drill II | Drill IV | Archery, Siege, Armored, Helicopter, Naval |
 | Drill IV | +2 First Strikes Suffers 20% Less Collateral Damage +10% vs. Mounted Units | Drill III | – | Archery, Siege, Armored, Helicopter, Naval |
 | Flanking I | +10% Withdrawal Chance | – | Flanking II Sentry Navigation I | Mounted, Armored, Helicopter, Naval |
 | Flanking II | +20% Withdrawal Chance Immune to First Strikes | Flanking I | Mobility | Mounted, Armored, Helicopter, Naval |
 | Formation | +25% vs. Mounted Units | Combat II or Drill II | – | Archery, Mounted, Melee, Gunpowder |
 | Guerilla I | +20% Hills Defense | – | Guerilla II | Recon, Archery, Gunpowder |
 | Guerilla II | +30% Hills Defense Double Movement in Hills | Guerilla I | Guerilla III | Recon, Archery, Gunpowder, Melee |
 | Guerilla III | +25% Hills Attack +50% Withdrawl Chance | Guerilla II | – | Archery, Gunpowder, Melee |
 | Interception I | +10% Interception Chance | – | Interception II | Gunpowder, Air |
 | Interception II | +20% Interception Chance | Interception I | – | Gunpowder, Air |
 | Leadership | +100% Experience from Combat | Great General | – | Recon, Archery, Gunpowder, Melee, Mounted, Siege, Armored, Helicopter, Naval |
 | March | Can Heal while Moving | Combat III or Medic I | – | Recon, Archery, Mounted, Melee, Siege, Gunpowder |
 | Medic I | Heal Units in Same Tile Extra 10% Damage/Turn | Drill I or Combat I | March Medic II | Recon, Archery, Mounted, Melee, Siege, Gunpowder, Naval |
 | Medic II | Heal Units in Adjacent Tiles Extra 10% Damage/Turn | Medic I | Medic III | Recon, Archery, Mounted, Melee, Siege, Gunpowder, Naval |
 | Medic III | Heal Units in Same and Adjacent Tiles Extra 15% Damage/Turn | Medic II and Great General | – | Recon, Archery, Mounted, Melee, Siege, Gunpowder, Naval |
 | Mobility | -1 Terrain Movement Cost | Flanking II | – | Mounted, Armored |
 | Morale | +1 Movement Range | Great General | – | Recon, Archery, Gunpowder, Melee, Mounted, Siege, Armored, Helicopter, Naval |
 | Navigation I | +1 Movement Range | Flanking I | Navigation II | Naval |
 | Navigation II | +1 Movement Range | Navigation I | – | Naval |
 | Pinch | +25% vs. Gunpowder Units | Combat I or Drill I and Gunpowder | – | Mounted, Gunpowder, Armored, Helicopter, Air |
 | Range I | +1 Operational Range | – | Range II | Air |
 | Range II | +1 Operational Range | Range I | – | Air |
 | Sentry | +1 Visibility Range | Combat III or Flanking I | – | Recon, Mounted, Helicopter, Naval |
 | Shock | +25% vs. Melee Units | Combat I or Drill I | – | Archery, Mounted, Melee, Siege |
 | Tactics | +30% Withdrawal Chance | Great General | – | Archery, Mounted, Melee, Siege, Gunpowder, Naval, Helicopter, Armored, Recon |
 | Woodsman I | +20% Jungle Defense +20% Forests Defense | – | Woodsman II | Recon, Melee, Gunpowder |
 | Woodsman II | +30% Jungle Defense +30% Forests Defense Double Movement in Jungle and Forests | Woodsman I | Woodsman III | Recon, Melee, Gunpowder |
 | Woodsman III | +2 First Strikes +50% Forests/Jungle Attack Heals Units in the Same Tile Extra 15% Damage/Turn | Woodsman II | – | Melee, Gunpowder |
Related Links:
More info about Promotions are available in the Civilization IV Info Center.