Monastir Offensive was an Allied military operation against the forces of the Central Powers during World War I, intended to break the deadlock on the Macedonian Front by forcing the capitulation of Bulgaria and relieving the pressure on Romania. The offensive took the shape of a large battle and lasted for three months and ended with the capture of the town of Monastir. On an average depth of 50 kilometers the Bulgarian First Army (from the end of September German Eleventh Army) gave battle on six occasions and was forced to retreat five times.