Hi Alex, thanks for translating; I have a few remarks :
S1 v.1 : I'm not sure if "a pale bum" is understandable in English, it would rather be "a petty thug" or something ; I would say for ex : He is a petty thug, an illusory lord ("he is" would be better than "it is')
S1 v.2 : I thing that "underground plots" would be better than "subterranean". It means hidden, concealed, secret.
S2 v.2 : "souverain" is not an English word, it would be "sovereign", but one could say it differently : the only Caesar, the only king to rule, etc.
S3 v.1 : "ses rivaux balayés" means that he swept his rivals aside
S3 v.2 : "seem" rather than "seems" (subject = the war and its [rumble ?])
S3 v.3 : rather "a" sickly obsession
S4 v.2 : normally it should be "while shaking the reins" (of the sleigh). I'm not sure whether one can use the singular here, even if of course the rhyme would be better.
Ce poème est bâti sur les rimes d'un sonnet de José-Maria de Heredia, L'Oubli.
Toute ressemblance avec une personne existante ne saurait être qu'une malheureuse coïncidence.