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

A Siege Onager knocking down trees.

The Siege 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 low movement and projectile speed, minimum range, high cost, and tendency to harm friendly units caught in its blast.

Siege Onagers can attack the ground and cut down trees, making them very useful in cutting a quick path to somewhere.

Unit availability
Available Unavailable

The * indicates that the civilization can fully upgrade their Siege Onagers, i.e. gets Siege Engineers. Faith and Heresy are not taken into account because they only contribute to their combat strength in a very situational manner.

The ^ indicates that the civilization has at least one civilization or team bonus or a unique technology that benefits the combat strength of the Siege Onager.

Tactics[edit | edit source]

Siegeonager anim aoe2.gif

Siege Onagers are arguably the most powerful siege weapon when it comes to killing other units. They 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 own melee units are usually endangered by the own Siege Onagers. But archers don't cover the Siege Onager's main weakness adequately, which is cavalry. Therefore, Siege Onagers are also often paired with Halberdiers. That combination is especially prominent with the Celts, Ethiopians, Koreans, and Slavs.

As Siege Onager is one of the most expensive upgrades in the game (but also one of the most powerful), the player has to carefully weigh whether it is worth it in a 1v1 game, but it can definitely turn the tide of a game with a few good shots in the right situation. Compared to the Onager, the Siege Onager has more health, damage, and pierce armor, but perhaps more importantly has a larger blast radius, making shots harder to dodge and able to hit more targets.

Upgrading to Siege Onager helps even out the playing field against one of the Mangonel-line's main weakness, the Bombard Cannon, to some extent. The reason for this is that the Siege Onager needs two attacks from a Bombard Cannon to be taken down, but can kill a Bombard Cannon in one full shot, while for the standard Onager it is the other way around. The large drawback of the much shorter range compared to the Bombard Cannon still remains however, so considering equal micromanagement skills and numbers, the Bombard Cannons should still come out on top. Another point to consider is invested resources: While the initial Siege Onager upgrade is very expensive, Bombard Cannons only require Chemistry (which is also useful for other ranged units), but Siege Onagers themselves are cheaper than Bombard Cannons, so in small numbers the Bombard Cannon is cheaper, but the higher the production numbers go, the more it evens out, until the cost of the Bombard Cannons actually surpasses the cost of Siege Onagers.

Siege Onagers are very effective against naval units. The AI will also use Siege Onagers as a shore defense to protect its buildings.

Siege Onagers are able to cut down trees, making them valuable in maps with large areas of forests like Black Forest by enabling to the player to attack from behind a forest.

Further statistics[edit | edit source]

Unit strengths and weaknesses
Strong vs. Buildings, Villagers, archers, units in dense formations
Weak vs. Melee units especially Magyar Huszars and other melee cavalry, Mangudai, Woad Raiders, Condottieri, Bombard Cannons, Eagle Warriors
Upgrades
Hit points Unique-tech-imperial.jpg Furor Celtica (+40%, Celts only)
Attack Siegeengineers.jpg Siege Engineers (+20% attack against buildings)
Chemistry.jpg Chemistry (+1)
Unique-tech-imperial.jpg Torsion Engines (increases blast damage radius, Ethiopians only)
Range Siegeengineers.jpg 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 Faith.jpg Faith
Heresy.png Heresy

Civilization bonuses[edit | edit source]

  • Aztecs: Siege Onagers are created 11.1% faster.
  • Celts: Siege Onagers fire 25% faster. Siege Onagers can convert herdables even if enemy units are next to them.
  • Slavs: Siege Onagers are 15% cheaper.

Team bonuses[edit | edit source]

Changelog[edit | edit source]

The Age of Kings[edit | edit source]

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

The Conquerors[edit | edit source]

The Forgotten[edit | edit source]

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

Trivia[edit | edit source]

  • The total cost to upgrade Mangonels to Siege Onagers is 2,250 food and 1,500 gold, making Mangonels the most expensive units to upgrade.
  • Despite the description given in the manual for the Siege Onager, it does not have any additional range over the Onager.
  • Before The African Kingdoms was released, the Siege Onager was the most exclusive unit in the game, i.e. no other unit was available to fewer different civilizations. With the introduction of The African Kingdoms, however, that title was lost to the Paladin. With the release of the Definitive Edition, however, the Siege Onager is tied with the Paladin as the most exclusive unit in the game. With update 36906, that title was won againt by the Siege Onager.
  • None of the four civilizations in Rise of the Rajas have access to the Siege Onager.

History[edit | edit source]

The siege onager was the largest upgrade of the onager line of weapons. It had the longest range and did the most damage.
Age of Empires II manual

In the Ancient Roman Empire, Onagers were designed to be used against lightly fortified towns, and massive armies, and thus the upgrade of this, armed the Onager with metal plates, were built twice the size and could fire medium and even large boulders to weaken walls that rams were not able to access. However, the Byzantines do not have access to the Siege Onager, despite being the Roman Empire's continuation.

In Medieval Times, Mangonels and Trebuchets were used in sieges as they proved to be more useful against large fortified walls.

Gallery[edit | edit source]

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