Synod of Diamper, held at Udayamperoor ((Diamper)), is a diocesan synod (council) that formally united the ancient Christian Church of the Malabar Coast (modern Kerala state), India, with the Roman Catholic church. It was convened on June 20, 1599, under the leadership of Aleixo de Menezes, Archbishop of Goa. Archdeacon George (of the Cross) was forced to comply with the wishes of Archbishop of Goa. This separated the Thomas Christians from the Chaldean Patriarch and subjected them directly to the Latin Archbishopric of Goa. The Archbishopric of Angamale was downgraded to a Bishopric under Goa in 1600 AD. Portuguese Padroado rule was thus imposed and the Bishops for Saint Thomas Christians were appointed by Portuguese Padroado.
Read more about Synod Of Diamper: Background, Decrees of The Synod, Social Influences of The Synod, Changes in Liturgy, Changes in Administration, Destruction of Syriac Books