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This article is about the unit in Age of Empires II. For the unit in Age of Mythology, see Onager (Age of Mythology).

Stronger than Mangonel. Wheeled siege weapon used to attack a small mass of units.
Age of Empires II description

The Onager is a ranged siege unit in Age of Empires II that can be trained at the Siege Workshop once the Imperial Age is reached. It is primarily used against large groups of enemies. Its high attack and splash damage make it a powerful unit, especially against archers and slow-moving units. Its main offsets are its projectile speed, minimum range, and tendency to harm friendly units caught in its blast. Onagers can attack ground and destroy trees.

Onagers are available to all civilizations except for the Huns and Turks.


Onagers are devastating against archers and slow-moving units, but cannot defend themselves against most melee units. Therefore, they need to be guarded in most situations. Archers are often used because the player's melee units can be damaged by their own Onagers if they are not careful. But archers do not cover the Onager's main weakness adequately, which is cavalry. Therefore, Onagers are also often paired with Halberdiers. That combination is used often with the Celts and Slavs, who both have bonuses affecting Onagers and Halberdiers.

Onagers are effective against naval units. The AI will often send out Onagers as a shore defense to protect its buildings.

While the Onager upgrade is fairly expensive at 800 food and a whopping 500 gold, it provides more attack, +1 range, +1 pierce armor, and slightly more HP. Since The Forgotten, Onagers are able to cut down trees, making them valuable in maps with large areas of forests like Black Forest by enabling the player to attack from behind a forest. It is visually distinguishable by a thicker more reinforced appearance. Overall it is a worthwhile upgrade when multiple Mangonels are being deployed.

Further statistics[]

Unit strengths and weaknesses
Strong vs. Buildings, Villagers, archers, Scorpions, Battering Rams, Trebuchets, units in dense formations
Weak vs. Melee units especially Magyar Huszars and other melee cavalry, Mangudai, Woad Raiders, Condottieri, Eagle Warriors, Bombard Cannons
Hit points Unique-tech-imperial.jpg Furor Celtica (+40%, Celts only)
Attack SiegeEngineersDE.png Siege Engineers (+20% attack against buildings)
ChemistryDE.png Chemistry (+1)
Unique-tech-imperial.jpg Torsion Engines (increases blast damage radius, Ethiopians only)
Unique-tech-imperial.jpg Counterweights (+15% attack, Saracens only)
Range SiegeEngineersDE.png Siege Engineers (+1)
Unique-tech-imperial.jpg Shinkichon (+1, Koreans only)
Armor CastleAgeUnique.png Ironclad (+4/+0, Teutons only)
Movement Speed Unique-tech-imperial.jpg Drill (+50%, Mongols only)
Conversion defense FaithDE.png Faith
HeresyDE.png Heresy
Upgrades SiegeOnagerDE.png Siege Onager

Civilization bonuses[]

  • Aztecs: Onagers are created 11% faster.
  • Bulgarians: Upgrading to Siege Onager costs -50% food.
  • Burmese: Researching Faith is 50% cheaper.
  • Celts: Onagers fire 25% faster. Onagers can convert herdables even if enemy units are next to them.
  • Chinese: Technologies that benefit Onagers are 20% cheaper.
  • Italians: Researching Chemistry is 33% cheaper.
  • Portuguese: Onagers cost -20% gold. Upgrades that benefit Onagers are researched 30% faster.
  • Slavs: Onagers are 15% cheaper.
  • Tatars: Onagers deal +25% bonus damage from cliffs and elevations.

Team bonuses[]


The Age of Kings[]

  • Onagers move at a speed of 0.5.
  • Researching Chemistry reduces the projectile speed from 3.5 to 2.9.

The Conquerors[]

The Forgotten[]

  • Onagers can cut down trees.
  • Researching Chemistry does not affect the projectile speed anymore.
  • Celts: Furor Celtica gives +40% HP to Onagers.
  • Teutons: Ironclad introduced.
  • A team containing Koreans: Onagers minimum range reduced by 2 (instead of +1 range).

Definitive Edition[]

Dynasties of India'[]


The onager was an improvement of the mangonel; it was larger, more powerful, and hurled a heavier payload for greater distance.
Age of Empires II manual

In reality, the Onager was invented long before the Mangonel, by the Ancient Romans. The Onager is credited as being the first Torsion Spring or Petraria Arcatinus-type catapult, as all catapults before that are called Ballistae and/or Scorpions.

The word Onager derives from the Greek onagros, meaning "wild ass". It was named after the famously untameable Onager or Asian wild ass (Equus hemionus), because it was said that the engine threw rocks as hard as the animal kicked.