Complex sentence: In 1375 he was summoned to attend another Council to consider the threat to the Pale from the O'Brien clan of Thomond, but he died the same year while on a visit to London.
Split into simpler sentences: In 1375 he was summoned to attend another Council to consider the threat to the Pale from the O'Brien clan of Thomond. He died later the same year while on a visit to London.