A series of tragic events occurred when the Buddha was 72 years old and in the 37th year of his teaching mission. This was the year when his cousin Devadatta initiated a schism in the ranks of the Sangha, then instigated a palace coup in the city of Rajagriha, the capital of the kingdom of Magadha, and finally made four attempts to assassinate the Buddha. These events were a great test of the Buddha’s wisdom, compassion, patience, equanimity, and ability to skillfully lead the Sangha in the face of external and internal threats to its survival and integrity.
It should be noted that doubts have been cast on the veracity of the legend of Devadatta as told in the canonical literature and commentaries of the various schools of Buddhism. Reginald Ray, basing himself on the work of earlier scholars, sums up the various accounts in his book Buddhist Saints in India: A Study of Buddhist Values & Orientation (link below).
According to Reginald Ray, it is possible that Devadatta was no relation nor even a contemporary of the Buddha, but may have been a strict proponent of the life of the forest renunciant who opposed the softer life of monastic Buddhism over a century after the Buddha’s passing. This Devadatta apparently created a Sangha that considered itself a separate and purer stream of Buddhism than the Sangha founded by Shakyamuni Buddha. Devadatta’s rival order still existed in India as late as the seventh century C.E. according to the testimony of the Chinese monk Hsuan-tsang (602-664).
A Condemned Saint: Devadata (pp. 162-173)
Buddhist Saints in India: A Study of Buddhist Values & Orientation