De Sesse was in command of an obsolete and weakly-defended Castello, which he surrendered to Ottoman admiral Sinan Pasha after two days of bombardment.

De Sesse and between 5,000 and 7,000 other people – the majority of the island's population – were subsequently enslaved, and he spent five years as a galley slave before being ransomed and freed.

This was unsuccessful as the messenger was intercepted and interrogated by the invading forces, and two days later the Ottomans began bombarding the Castello where de Sesse and the majority of Gozo's population were taking refuge.

[9] The castle's defences were obsolete and it was not adequately manned, and after it became clear that no relief from Malta would be forthcoming, de Sesse and the Gozitan elites decided to ask for a truce.

Contrary to expectations, the Ottomans spared 40 elderly men rather than the elites, and they proceeded to sack the Castello and enslave the people inside, who numbered between 5,000 and 7,000 according to different sources.