In 1616, Dutch explorers Willem Schouten and Jacob Le Maire became the first Europeans to sight the islands. The main island was named after French admiral Louis Antoine de Bougainville, who reached it in 1768. The German Empire placed Bougainville under a protectorate in 1886, while the remainder of the Solomon Islands became part of the British Empire in 1893. The present-day boundaries between Papua New Guinea and Solomon Islands were established by the Tripartite Convention of 1899. The incorporation of Bougainville into German New Guinea initially had little economic impact, although the associated Catholic missions succeeded in converting a majority of the islanders to Christianity.