[1] As part of their defensive plans the Venetians separated the promontory from the rest of the city of Corfu by creating the Contrafossa, a moat which is a sea channel connecting the Gulf of Kerkyra to the North with the Bay of Garitsa to the South, converting the citadel into an artificial island.

[1] The earliest indication of fortifications on the site presently occupied by the Old Fortress dates from around the 6th century AD, after the destruction of the ancient city of Corcyra by the Ostrogoths.

[1] Following the Gothic invasion and until the 13th century, the medieval town of Corfu developed within the boundaries of the peninsula which today is occupied by the Old Fortress.

[1] Following the first siege of Corfu by the Ottomans in 1537, the Venetian governor ordered the construction of new defensive zones incorporating new bastions and towers which exist to this day.

[1][2] In 1537, during the Third Ottoman–Venetian War, Sultan Suleyman the Magnificent dispatched a force of 25,000 men under the command of admiral Hayreddin Barbarossa to attack Corfu.

The Ottomans landed at Govino Bay, present day Gouvia, and proceeded toward Corfu town, destroying the village of Potamos as they made their way toward the city.

[4] The Old Fort, Corfu city's only fortification during that period, and the castle of Angelokastro were the only two places on the island not in the hands of the invaders at the time.

[5] Even at the Old Fortress, women, children and the elderly, called the inutili (useless) by the Venetians, were turned away and left outside the fort to die or be enslaved.

In anticipation of the attack, Venice appointed Count Johann Matthias von der Schulenburg in charge of the defence of the fort.

The Ottomans upon landing in Corfu established themselves in strategic positions and installed artillery situated on the nearby hills of Avrami and Sarocco and started bombarding the citadel.

[12] The Venetian commander of the fortress, Captain Andrea Pisani, brother of the Doge of Venice Alvise Giovanni Mocenigo, was killed along with members of his staff.

When they heard the ultimatum, some Jewish people escaped to the countryside of Corfu but most, fearing for their families, went the morning of the 9th of June to the old Fort, as they had been told.