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Heresy is a technology in Age of Empires II: The Conquerors that can be researched at the Monastery. Once researched, it causes own units that have been converted by an enemy Monk or Missionary to die instead of joining the opposing player. Converted buildings are destroyed.

Heresy is very useful, as it prevents the player's converted units from being able to attack and distract remaining troops. The technology helps minimize losses. Players should research Heresy if they anticipate an enemy attempt to Monk rush.

Given its high cost, especially for the Castle Age, however, it is not recommended to research Heresy if opposing players do not regularly use Monks for conversion purposes.

Technology availability
Available Unavailable

As seen in the table above, Heresy is notably absent from the technology trees of most civilizations with access to powerful units like elephants, with the sole exception of the Malay (whose Battle Elephants are the weakest) and Gurjaras (who lack Faith).

Conversely, nearly all civilizations with Paladins have access to Heresy, with also only two exceptions: the Burgundians and the Persians.

Civilization bonuses[]

Team bonuses[]


  • With Heresy researched, the Bulgarian Konnik dies when converted, but still turns into a Dismounted Konnik that belongs to the original owner instead of the converting player.
  • Among the civilizations introduced in Age of Empires II HD: Rise of the Rajas, only the Malay have access to Heresy. This may be a reference to books and studies written by scholars such as Marmaduke Dodsworth, who state that the Malay people are historically very resistant to conversion.
  • The fact that civilizations with elephant units often lack Heresy could be a reference to how elephants would often panic in battle and trample soldiers on their own side.
  • Heresy’s icon says [De] plurimis claris selectisque mulieribus opus prope divinum [novissime] congestum, which is the full title of a book of biographies written by Giovanni Boccaccio that roughly translates to ‘Concerning many famous and select women, a nearly divine work very recently gathered.’
  • Neither of the two civilizations introduced in Lords of the West have Heresy.


As the Middle Ages progressed, Christianity in Europe faced a number of challenges, including heresy. This word came into use in the 13th century to define an opinion or doctrine that was contrary to church dogma. New opinions popped up at an alarming rate. Philosophers studying the Bible suggested new interpretations. Contact with pagan beliefs led to distortions of dogma in the hinterlands. Anyone who attempted to newly interpret the lessons of the Bible risked being accused of heresy. Coming to believe in a heretical position was seen by church leaders as a supreme sin, and many people condemned as heretics were burned at the stake.
The Conquerors manual