Construction of the fortress began in 1790 and the fortress was inaugurated in 1795. The fortress
place was changed to Eagle Island, which is the forest was growing pasture and wooded land. Kotkansaari was previously inhabited only by Sapokanlahden beach, which was located in Kotka Croft. The resident of the sources mentioned for the first time in the late 1600s. Naval barracks, and the harbor was built in the eastern part of the island. The urban community was formed in the northern part of the island. Construction fell silent Paul I, ruler of the years 1796-1801, but picked up again Alexander I during the years 1801-1809.
Kotkansaari has been estimated at around 10 000 people before Finnish war. Fortress lost its importance after the Finnish war in the 1810s.
The fortress was destroyed in 1855 during the Crimean War.
Kotka founded on the island in 1879 .