Complex sentence: The exact date of his death is unknown, but the last date in his chronicle dates to 1552, though it is generally believed he was still present in Calais when the city was retaken in 1558.
Split into simpler sentences: The exact date of his death is unknown, but the last date in his chronicle is 1552. It is, however, generally believed that he was still present in Calais when the city was retaken in 1558.