In 1937, Philip's sister Cecilie, her husband Georg Donatus, Hereditary Grand Duke of Hesse, her two young sons, Ludwig and Alexander, her newborn infant, and her mother-in-law, Princess Eleonore of Solms-Hohensolms-Lich, were killed in an air crash at Ostend; Philip, then 16 years old, attended the funeral in Darmstadt.