The Kingdom of Travancore ( /ˈtrævəŋkɔər/; Malayalam: തിരുവിതാംകൂർ, tiruvitāṁkūr ? ) was a former Hindu feudal kingdom (till 1858) and Indian princely state that had been ruled by the Travancore Royal Family from the capital at Padmanabhapuram or Thiruvananthapuram. The Kingdom of Travancore at its zenith comprised most of modern day southern Kerala, Kanyakumari district, and the southernmost parts of Tamil Nadu. The official flag of the state was red with a dextrally-coiled silver conch shell (Turbinella pyrum) at its centre. The king of the state was accorded 19-gun salute, the second highest among the honorary gun salutes that were granted by the British Empire to honour the heads of the princely states. The state government took many progressive steps in the socioeconomic front and the state was one among the best of princely states, with reputed achievements in education, political administration, public work and social reforms.
King Marthanda Varma (1729–1758) founded the modern Kingdom of Travancore by militarily expanding the Kingdom of Venad. He hailed from the Kingdom of Thrippappur, one of the branches of the Venad royal family, who trace their origin back to the Ay kingdom and the Later Chera kingdom. In 1741, Travancore won the Battle of Colachel against the Dutch East India Company, resulting in the complete eclipse of Dutch power in the region. In this battle, the admiral of the Dutch, Eustachius De Lannoy, was captured; later he was utilized to modernize the Travancore army by introducing better firearms and artillery. The Travancore-Dutch War (1739–1753) is the earliest example of an Asian state overcoming a European power in war. Travancore became the most powerful state in the Kerala region by defeating the Zamorin of Calicut in a battle at Purakkad. Ramayyan Dalawa, the Prime Minister (1737–1756) of Marthanda Varma, also played an important role in this consolidation and expansion. Travancore often allied with the English East India Company in military conflicts. During the reign of Dharma Raja, Marthanda Varma's successor, Tipu Sultan, the de facto ruler of Kingdom of Mysore and the son of Hyder Ali attacked Travancore as a part of the Mysorean invasion of Kerala; this led to the famous Third Anglo-Mysore War, as Travancore had already allied with the British to seek protection from the potent assault from Tippu. In 1808 Travancore witnessed an armed rebellion against the British under the leadership of Velu Thampi Dalawa, the Prime Minister of Travancore, but was successfully quelled with the help of the British.
Chithira Thirunal, the last king of Travancore, made the Temple Entry Proclamation in 1936 abolishing the ban on low-caste people from entering Hindu Temples. At the same time, C. P. Ramaswami Iyer, Chithira Thirunal's Prime Minister, is remembered for the ruthless suppression of a local struggle organised by the Communists, known as the Punnapra-Vayalar uprising. When United Kingdom accepted demands for a partition and announced its intention to quit India, the king of Travancore, Chithira Thirunal, issued a declaration of independence on June 18, 1947. The declaration was unacceptable to the Government of India; many rounds of negotiation were conducted among the diwan, C. P. Ramaswami Iyer, and the Indian representatives. In July 23, 1947 they decided in favour of the accession to the Indian Union, pending approval by the king. An assassination attempt on the diwan by the Communists on the July 25, 1947 caused to hasten the accession of Travancore state to the Indian Union. Travancore and the princely state of Cochin merged on 1 July 1949 to form the Indian state of Travancore-Cochin. Later Travancore-Cochin joined with the Malabar district of the Madras State (modern day Tamil Nadu), on 1 November 1956, to form the Indian state of Kerala.