The Portuguese conquest of the Jaffna kingdom occurred after Portuguese traders arrived at the rival Kotte kingdom in the southwest of modern Sri Lanka in 1505. Many kings of Jaffna, such as Cankili I, initially confronted the Portuguese in their attempts at converting the locals to Roman Catholicism, but eventually made peace with them.
By 1591, the king of Jaffna Ethirimanna Cinkam was installed by the Portuguese. Although he was nominally a client, he resisted missionary activities and helped the interior Kandyan kingdom in its quest to get military help from South India. Eventually, a usurper named Cankili II resisted Portuguese overlordship only to find himself ousted and hanged by Phillippe de Oliveira in 1619. The subsequent rule by the Portuguese saw the population convert to Roman Catholicism. The population also decreased due to excessive taxation, as most people fled the core areas of the former kingdom.
Initial contact
Portuguese traders reached Sri Lanka in 1505; their initial forays were against the southwestern coastal Kotte kingdom, which enjoyed a lucrative monopoly on the spice trade, which was also of interest to the Portuguese. The Jaffna kingdom came to the attention of Portuguese officials in Colombo for multiple reasons, which included their interference in Roman Catholic missionary activities (which was assumed to be supporting Portuguese interests), the lucrative markets and strategic benefits of Jaffna's Vannimai chieftaincies, and their support of anti-Portuguese factions within the Kotte kingdom, such as the chieftains from Sitawaka. By the late 16th century, Portuguese influence strengthened in the courts of the Kandyan and Kotte kingdoms and some of Jaffna's Vannimai chieftaincies were subdued by these kings. The Jaffna kingdom functioned as a logistical base for the Kandyan kingdom, located in the central highlands without access to any seaports. They gained access to the seaports of Trincomalee and Batticaloa in the east, but the Jaffna peninsula proved more convenient as an entry port for military aid arriving from South India. Furthermore, it was feared by the Portuguese that (due to its strategic location) the Jaffna kingdom might become a beachhead for Dutch landings. It was king Cankili I who resisted contacts with the Portuguese, and even massacred six to seven hundred Parava Catholics in the island of Mannar. These Catholics had been brought from India to Mannar to take over the lucrative pearl fisheries extending to Puttalam from the Jaffna kings.
Client state
The first expedition, led by Viceroy Dom Constantino de Bragança in 1560, failed to subdue the kingdom but captured Mannar Island. Although the circumstances are unclear, by 1582 the Jaffna king was paying a tribute to the Portuguese of ten elephants or an equivalent in cash. In 1591, during the second expedition, led by André Furtado de Mendonça, King Puvirasa Pandaram was killed and his son Ethirimanna Cinkam was installed as the monarch. This arrangement gave the Catholic missionaries freedom of action and monopoly in elephant export to the Portuguese, which the incumbent king, however, resisted. He helped the Kandyan kingdom under kings Vimaladharmasuriya I and Senarat (1604–35) during the period 1593–1635 with the intent of securing help from South India to resist the Portuguese. He, however, maintained autonomy of the kingdom without overtly provoking the Portuguese.
End of the kingdom
With the death of Pararasasekaran in 1617, Cankili II, an usurper, took control of the throne after killing the regent nominated by the Ethirimanna Cinkam. Unable to secure Portuguese acceptance of his kingship, Cankili II through Migapulle Arachchi invited military aid from the Thanjavur Nayaks and the Karaiyars, and allowed them to use a base in Neduntivu, hence posing a threat to Portuguese shipping routes through the Palk Strait. The Portuguese accounts refer to six attempts made by rebels to install a local prince on the Jaffna throne in the years 1620 and 1621. At first, the chief of Karaiyars rose in revolt and offered resistance to the Portuguese, with the help of a large troops of Thanjavur Nayaks. Phillippe de Oliveira is said to have defeated him near Nallur.