The Western Schism, also known as the Papal Schism, the Great Occidental Schism, the Schism of 1378, or the Great Schism, was a split within the Catholic Church lasting from 20 September 1378 to 11 November 1417, in which bishops residing in Rome and Avignon simultaneously claimed to be the true pope, and were eventually joined by a third line of Pisan claimants in 1409.
