The Northern Solomons were the more northerly group of islands in the Solomon Islands archipelago over which Germany declared a protectorate in 1885. Initially the German Solomon Islands Protectorate included Choiseul, Santa Isabel, the Shortlands and Ontong Java Islands, but in 1900 these islands were transferred to the British Solomon Islands Protectorate. The largest of the Solomon Islands, Bougainville, continued under German administration until World War I when it fell to Australia, and after the war, it formally passed to Australian jurisdiction under a League of Nations mandate.
Today, the original North Solomon Islands are split between the Autonomous Region of Bougainville in Papua New Guinea and the successor state of the British Solomon Islands which was officially renamed from the British Solomon Islands Protectorate to Solomon Islands in 1975 prior to becoming an independent, sovereign state in 1976.
On 17 February 1568, the archipelago was discovered by Spanish explorer Alvaro de Mendaña y Neyra, who named its Islas de Salomon.
In April 1885 a German protectorate (Schutzgebiet) was declared over the northern Solomon Islands: Bougainville, Buka, Choiseul, Santa Isabel and Ontong Java.
In 1893 the British declared a protectorate over the southern Solomon Islands of New Georgia, Guadalcanal, Malaita and San Cristobal, and this protectorate became known as the British Solomon Islands Protectorate. In 1898 Britain annexed the Santa Cruz and the Rennell and Bellona Islands.
In the year 1900, under the terms of Treaty of Berlin (14 November 1899), Germany transferred Choiseul, Santa Isabel, the Shortlands and Ontong Java Islands to the British Solomon Islands Protectorate, but retained Bougainville and its surrounding islands. Germany granted this claim in exchange for the British giving up all claims to Samoa.
The Roman Catholic Apostolic Prefecture of the Northern Solomon Islands was established on 23 May 1898, by separation from the Apostolic Vicariate of New Pomerania, including the Islands of Ysabel, Choiseul, Bougainville and all the islets under German protectorate; until 1904, it was named Apostolic Prefecture of German Solomon Islands.
In 1897 the islands were put under the jurisdiction of Mgr Broyer, Apostolic Vicar of Samoa, and in 1898 formed into a new prefecture under Mgr Joseph Forestier, who resided at Kieta, on Bougainville Island. Fever was so prevalent at the mission that most of the fathers who went to the islands in 1898 were carried off by disease.
In 1911 the mission contained: 3 churches; 3 stations; 10 Marist Fathers; 5 lay brothers; 7 sisters of the Third Order of Mary; 2 Samoan catechists; 5 Catholic schools, with 140 pupils; 2 orphanages; and a few hundred Catholics. The Marist missionaries belonged to the Province of Oceania, the superior of which resided at Sydney, New South Wales.
In 1930, it was promoted to Apostolic Vicariate of Northern Solomon Islands, from which the present Roman Catholic Diocese of Bougainville stems.