In Ancient times, the island played a minor role during the Persian Wars. In 480 BC, the fleet of the Persian King Xerxes was hit by a storm and was badly damaged on the rocks off the Skiathos coast. Following this the Greek fleet blockaded the adjacent seas to prevent the Persians from invading the mainland and supplying provisions to the army facing the 300 Spartans defending the pass at Thermopylae. The Persian fleet was defeated there at Artemisium and finally destroyed at the Battle of Salamis a year later. Skiathos then became part of the Delian League. This original city was destroyed by Philip V of Macedon in 200 BC.
In 1207 the Ghisi brothers captured the island and built the Bourtzi, a small Venetian-styled fortress similar to the Bourtzi in Nafplio, on an islet just out of Skiathos Town, to protect the capital from the pirates. But the Bourtzi was ineffective in protecting the population and in the mid-14th century the inhabitants moved the capital from the ancient site that lay where modern Skiathos Town is to Kastro (the Greek word for castle), located on a high rock, overlooking a steep cliff above the sea at the northernmost part of the island. The island returned to Byzantine control in the 1270s, and remained in Byzantine hands until after the Fall of Constantinople in 1453, when it passed to the Republic of Venice. Like the rest of the Northern Sporades, Skiathos was conquered by the Ottoman admiral Hayreddin Barbarossa in 1538.
Bourtzi
Kastro
In 1704 monks from Athos built the Evangelistria Monastery, which played a part on the Greek War of Independence as a hide-out for Greek rebels. The first flag of Greece was created and hoisted in the Evangelistria Monastery in Skiathos in 1807, where several prominent military leaders (including Theodoros Kolokotronis and Andreas Miaoulis) had gathered for consultation concerning an uprising, and they were sworn to this flag by the local bishop.
Evangelistria Monastery
After the War of Independence and demise of piracy in the Aegean, Kastro became less important. In 1830s, the island's capital was moved to the original site — where it still remains. Today, the ruins of Kastro are a tourist attraction.
During the 19th century Skiathos became an important shipbuilding centre in the Aegean due to the abundance of pine forests on the island. The pine woods of the island were then almost obliterated. This was brought to a halt though, due to the emergence of steamboats. A small shipwright remains north of Skiathos Town, which still builds traditional Greek caiques.