Complex sentence: His protests were, however, ignored by the revolutionaries and it was as "Citizen Louis Capet" that he was officially known in the last year of his life and under it he was finally sentenced to death and exceuted.
Split into simpler sentences: His protests were, however, ignored by the revolutionaries. It was as "Citizen Louis Capet" that he was officially known in the last year of his life, and under this name he was finally sentenced to death and exceuted.