Manuel is noted for his role in a diplomatic interplay between the Nicaean emperor Theodore I Laskaris and the Latin Emperor of Constantinople, Robert of Courtenay, in 1222. Robert had approached Theodore for a peace treaty and the latter offered his daughter Eudokia in marriage to cement the deal. But Theodore had married Maria of Courtenay, Robert's sister, in 1217. Manuel is thus reported by George Akropolites to have blocked the betrothal, twice negotiated, on religious-legal grounds: Robert, Theodore's brother-in-law, could not also become his son-in-law as this was an 'illegal union' and constituted incest as it was within the third degree of kinship.George Akropolites (Ruth Macrides, ed). The History. Oxford: University Press, 2007. Editor's notes, pp. 158.
