His rule ended with a coup by his brother Ghezo who then erased Adandozan from the official history resulting in high uncertainty about many aspects of his life.
Dealing with the economic depression that had defined the administrations of his father Agonglo and grandfather Kpengla, Adandozan tried to reduce slavery to decrease European trade, and when these failed reform the economy to focus on agriculture.
Unfortunately, these efforts did not end domestic dissent and in 1818 at the Annual Customs of Dahomey, Ghezo and Francisco Félix de Sousa, a powerful Brazilian slave trader, organized a coup d'état and replaced Adandozan.
[1] Maurice Ahanhanzo Glélé says that Adandozan was replaced because he had failed economically and then decided to sacrifice his sister, Sinkutin, to have her plead his case to the ancestors.
In reality there was apparently significant violence in the coup between different factions and many of Adandozan's sons and his entire group of female bodyguards were executed by Ghezo.
[3] He lived much of his later life confined to the palaces, while his descendants changed their name to avoid association, and when he died he was buried quickly but with full royal honors.
[2][4] Historian Edna Bay writes that after the coup "Adandozan suffered a bizarre punishment that was perhaps worse than assassination--to watch history be reworked as though he had never lived.
[5] The traditional stories about Adandozan's rule (which are retold, with some changing of names, in Bruce Chatwin's novel The Viceroy of Ouidah) portray him as extremely cruel: he is said to have raised hyenas to which he would throw live subjects for amusement; he is pictured slitting a pregnant woman's abdomen open on a bet to see whether he could predict the sex of the fetus.
[7] A large cache, found in the Instituto Historico e Geografico Brasileiro and Biblioteca Nacional in Rio de Janeiro, and several of the letters in this collection were examined in an article published by historian Ana Lucia Araujo in the British journal Slavery and Abolition.
[8] The full text of Adandozan's letters, both from the Institute cache and other repositories, as well as a few from his predecessor Agongolo and his successor Gezo were published in (the original) Portuguese in 2013.
[9] La vie, le règne et l'œuvre de Dàdà Adàndozàn : Vingt-et-un ans effectifs de règne (1797-1818), deux cents ans d'ostracisme (1818-2018) : Actes du colloque tenu à l'Université d'Abomey-Calavi, Campus d'Abomey-Calavi, les 27, 28 et 29 mars 2014, pref.