Castel dell'Ovo
About 1376, he married Joanna of Durazzo, daughter of Charles, Duke of Durazzo. Robert IV inherited the County of Eu on April 6, 1387 along with Saint-Valery and Ault, however, in Naples at the time, he never learned of his father's death. He and his wife were poisoned whilst staying at Castel dell'Ovo on July 20, 1387 on the orders of Joanna's own sister Margaret, Queen Regent of Naples. Robert and Joanna were buried in the church of San Lorenzo Maggiore in Naples.