According to tradition, the Benedictine abbey of Herrenchiemsee was established about 765 by Duke Tassilo III of Bavaria at the northern tip of the Herreninsel. New findings however indicate an even earlier foundation around 620-629 by the missionary Saint Eustace of Luxeuil.
In 969 Emperor Otto I consigned the abbey to the Archbishops of Salzburg, who in about 1130 re-established Herrenchiemsee as a monastery of Canons Regular living under the Augustinian rule. In 1215, with the approval of Pope Innocent III, Prince-Bishop Eberhard von Regensburg made the monastery church the cathedral of a diocese in its own right, the Bishopric of Chiemsee, including several parishes on the mainland and in Tyrol.
In the course of the German Mediatisation, Herrenchiemsee Abbey was secularised in 1803 and the Chiemsee bishopric finally dissolved in 1808. The island was then sold; various owners demolished the cathedral and turned the abbey into a brewery. Plans for the complete deforestation of the island were blocked by King Ludwig II, who acquired Herrenchiemsee in 1873. He had the leftover buildings converted for his private use, the complex that later became known as the 'Old Palace', where he stayed surveying the construction of the New Herrenchiemsee Palace.
References:Towering 52 meters above the sea, Bengtskär lighthouse is the tallest one in Scandinavia. The building started in in 1905 after the shipwreck of S/S Helsingfors and was completed in 1906. The lighthouse was designed by architect Florentin Granholm. On December a special petrol lantern, designed and built in Paris, was brought to Bengtskär and installed atop the tower.
German fleet bombarded Bengstkär in the First World War in 1914. Since the Gulf of Finland was heavily mined, it was not until 1919 that the surrounding seas were declared safe for shipping, that the light was lit again.
After the war the military value of Bengtskär increased as part of the defence system of independent Finland. In Second World War (1941) Soviet Union made a suprise attack to island. After a bloody battle, the small Finnish garrison emerged victorious. Intermittent repairs to the facility continued during the post-war period.