There has been an ancient acropolis of Myrina since the 13th century BC. The medieval castle was first built by the Byzantines in the beginning of the 12th century. A lot of materials came from the acropolis which disappeared.
Following the dissolution and division of the Byzantine Empire after the Fourth Crusade, Lemnos was apportioned to the Latin Empire, and given, in 1207, as a fief to the Venetian Navigajoso family.
During the last centuries of Byzantium, Lemnos played an important role in the recurring civil wars of the 14th century. Following the Fall of Constantinople to the Ottomans in 1453, the island was added to the domain of the Gattilusi of Lesbos, but following the fall of the Despotate of the Morea, Sultan Mehmed II conquered the islands of the North Aegean too and gave Lemnos as a domain to the brother of Thomas, last legitimate Despot of Mystras (and his ally) Demetrios Palaiologos, in 1462.
The island then fell under Venetian control. In 1476, the Venetians and the island's Greek inhabitants successfully defended Kotsinos against a Turkish siege, but the island was ceded to the Ottomans by the 1479 Treaty of Constantinople which ended the First Ottoman-Venetian War.
During the Sixth Ottoman-Venetian War, after a major victory in Dardanelles over the Ottoman fleet, the Venetians captured the island again on 20 August 1656, but the Turks recovered it barely a year later, on 31 August 1657, after a siege of 36 days. In 1770, Kastro was besieged by Count Orlov during the Russo-Turkish War of 1768–1774, during the so-called Orlov events. The walls of the castle were severely damaged in that siege.
In 1780, Hasan Gatzi pasha repaired the castle and equipped it with 150 canons.
On 8 October 1912, during the First Balkan War, Lemnos became part of Greece. The Greek navy under Rear Admiral Pavlos Kountouriotis took it over without any casualties from the occupying Turkish Ottoman garrison, who were returned to Anatolia. Lemnos became a forward anchorage for the Greek fleet, which enabled it to keep watch on the Dardanelles and prevent a foray by the Ottoman Navy into the Aegean. It was a crucial factor in the victory in the Balkan Wars.
Lemnos was the main military base of the allied forces in the ill-starred Gallipoli campaign against the Turks in WW I.References:
Goryōkaku (五稜郭) (literally, 'five-point fort') is a star fort in the Japanese city of Hakodate on the island of Hokkaido. The fortress was completed in 1866. It was the main fortress of the short-lived Republic of Ezo.
Goryōkaku was designed in 1855 by Takeda Ayasaburō and Jules Brunet. Their plans was based on the work of the French architect Vauban. The fortress was completed in 1866, two years before the collapse of the Tokugawa Shogunate. It is shaped like a five-pointed star. This allowed for greater numbers of gun emplacements on its walls than a traditional Japanese fortress, and reduced the number of blind spots where a cannon could not fire.
The fort was built by the Tokugawa shogunate to protect the Tsugaru Strait against a possible invasion by the Meiji government.
Goryōkaku is famous as the site of the last battle of the Boshin War.