Complex sentence: On 15 January 1822, he was elected president of the legislative assembly; but the ill-success of his campaign in central Greece, and his failure to obtain a commanding position in the national convention of Astros, led to his retirement early in 1823.
Split into simpler sentences: On 15 January 1822, he was elected president of the legislative assembly. However, due to the failure of his campaign in central Greece, and his failure to obtain a commanding position in the national convention of Astros, he was compelled to retire in 1823.