The attack, which was led by Sinan Pasha, Salah Rais and Dragut, appears to have been launched in retaliation for the capture of Mahdia by the Spanish and Hospitallers the previous year.

[1] Prior to the 1551 attack, Gozitan society included a few noble families who were of Sicilian origin, while most of the population were peasant farmers known as beduini who owned small parcels of land.

[3] At the time of the attack, most of Gozo's population lived in one town which consisted of a medieval fortress known as the Castello and a suburb known as the Borgo (now collectively known as Victoria or Rabat).

[3] A cavalry force of 30 Hospitaller knights and 400 Maltese volunteers led by the English commander Upton and 100 knights and 300 arquebusiers on foot led by the Spanish commander De Guimeran engaged the Ottomans in an attempt to prevent them from landing on the otherwise undefended Sciberras Peninsula, but they retreated to the Hospitaller base at nearby Birgu upon seeing the invaders' numerical superiority.

[11] The Ottomans were able to land and they briefly occupied the peninsula,[13] from where they reconnoitered Birgu and determined that the city's defences – consisting of Fort St. Angelo and newly-built fortifications – were too strong for it to be easily conquered.

The latter was reluctant to send a substantial number of reinforcements, but Nicolas Durand de Villegaignon and six other knights were sent and they managed to sneak past the Ottomans into the city.

[7] According to Bosio, Sinan Pasha deployed artillery near the Porta Reale and the parish church of St George, and the Castello began to be bombarded on Friday 24 July.

De Sesse convened a council meeting with Gozo's elites, and they decided to seek a truce with the invaders on the condition that 200 of the wealthier citizens be spared and allowed to keep their possessions.

[3] On Sunday 26 July, after two days of bombardment, de Sesse and the Gozitan elite decided to accept Sinan Pasha's terms and the Castello's gate was opened.

[2] Sources disagree on the exact number: Bosio stated that 5,000 were enslaved while 18th-century Gozitan historian Giovanni Pietro Francesco Agius de Soldanis gave a figure of 6,000 to 7,000.

[7] A number of surviving court cases and other records from the 1550s and 1560s make reference to Gozitan slaves in the Ottoman capital, including some who were eventually freed or ransomed, some who converted to Islam, and others who died in slavery.

[10] The archives of the Mdina cathedral indicate that in the years after the attack, the Church in Malta collected money in order to ransom some of the slaves, but it did not manage to raise sufficient funds to secure the release of a substantial number of captives.

[7] There are records of some richer Gozitans being ransomed shortly after their capture, including priest and notary Lorenzo de Apapis who returned to Malta by October 1553.

The charges against him were eventually dropped after his conduct was deemed to have been reasonable considering the superiority of the enemy forces, and he was released by Claude de la Sengle on 14 August 1557.

Many of the Maltese settlers on Gozo originated from rural areas on the main island, including Naxxar, Mosta and Għargħur in the north, Żebbuġ and Siġġiewi in the centre, and Żurrieq, Safi and Qrendi in the south.

[17] Some of the commonest surnames on Gozo as of the early 21st century[20] – including Attard, Camilleri, Portelli, Azzopardi and Spiteri – are not mentioned in any pre-1551 Gozitan records, and they are believed to have been introduced to the island by Maltese settlers following the 1551 attack.

[21] Grand Master de Homedes evacuated non-combatants to Syracuse and Licata in Sicily, and the Order's Council decided to focus its efforts on improving the fortifications of Malta in case of another attack.

[1] Viceroy of Sicily Juan de Vega sent the military engineer Pietro Prado to Malta, and in January 1552 the latter reviewed the island's defences together with a commission of Hospitaller knights.

"[16] Although there are claims that some saw these looted documents in Constantinople during the 19th century, the relocation of Gozitan records to the Ottoman capital has not been verified, and several attempts by the British colonial government of Malta to retrieve them were unsuccessful.

Following an 1848 petition by Baron Giuseppe Maria Depiro, Governor Richard More O'Ferrall requested the colonial secretary Earl Grey to assist him in locating any surviving Gozitan records in Constantinople.

In 1849 the Earl wrote to O'Ferrall that following enquiries made by the British ambassador, "it appears that no such documents as those supposed to have been taken from the island of Gozo in the year 1551 are in existence in that capital.

"[16] Lewis Mizzi, a Maltese lawyer who lived in Constantinople in the late 19th century, was later tasked with finding these documents by secretary Henry Houlton, but his two-decade-long search proved to be unsuccessful.

The fact that poorly-defended Mdina managed to hold out was attributed by some to divine intervention;[9] similar legends had previously arisen from an earlier siege of the city in 1429.

[18] There are also legends related to buried treasure including precious objects from the Matrice church and a bell from Żebbuġ which were supposedly hidden by Gozitans prior to the attack but which were never recovered.

[25] A plaque with an Italian inscription and a fleur-de-lis commemorating Bernardo de Opuo was installed on the façade of his former residence within the Castello by Gozo's Università in July 1579.

[3] Another monument commemorating the victims of the attack designed by artist John Grima was installed outside the walls of the Cittadella in 2016 as part of a major restoration project.

[3][26] The 1551 attack is featured in a number of historical fiction books, including The Disorderly Knights (1966) by Dorothy Dunnett, and Eight Pointed Cross (2011),[27] Falcon's Shadow (2020)[28] and Ash Fall (2022) by Marthese Fenech.