Complex sentence: The death of John's sister, Teresa Maria, in February 1704, greatly saddened him and caused him to avoid appearing at court for some months and to estrange himself from his father, who favoured John's younger brother, Manuel, Count of Ourém.
Split into simpler sentences: The death of John's sister Teresa Maria in February 1704, greatly saddened him. It caused him to avoid appearing at court for some months and to estrange himself from his father, who favoured John's younger brother, Manuel, Count of Ourém.