The Thracian question is an integral part of the Bulgarian national question and is a conditional indication of the struggle of the Bulgarians from Thrace to liberate them from Ottoman domination. The successful completion of the Eastern Rumelia Union with the Principality of Bulgaria in 1885 gave the struggling Thracians the hope that they would be able to achieve their liberation. They took an active part in the Ilinden–Preobrazhenie Uprising in 1903.