Ah, that's a reference to the Mad Queen of Madagascar, who turned up in one of the Flashman novels.
The lady in question was the infamous Queen Rabodoandriana Impoin-I-Merina Ranavalona I, and if you can say that without pausing for breath even when sober, I doff my hat to you. She was quite fond of the Machiavelli approach to statehood, including a fair amount of blood-letting. From all accounts, she was a sort of African version of Erzébet Bathory, though I don't recall her being fond of bathing in the blood of virgins. She was, however, utterly ruthless: she seized the Malagasy crown by intrigue, skulduggery and possibly a spot of poisoning along the way, moved swiftly to round up her opponents and have them executed, then spent most of her reign engaged in rampant pillaging of opposing tribes and indulging in such niceties as re-legalising the slave trade, which provided much of the funding for her military campaigns. To say that this woman was utterly psychotic merely dwells upon the banally obvious, as any scholarly account of her activities readily reveals. Probably one of the most hideous human beings to have walked on the face of this planet, it's just as well she only had access to African levels of technology, because if she'd had European weapons at her disposal, she would doubtless have scaled the sort of dizzy genocidal heights that are more usually associated with 20th century despots.