the islands for centuries were above all a place of confinement. In Roman times the islands were known as Trimerus which derives from the Greek trimeros, τρίμερος meaning "three places" or "three islands". Emperor Augustus relegated his niece Giulia there who died after twenty years of forced residence. In 780 Charlemagne exiled Paolo Diacono who, however, managed to escape.

The history of the archipelago, however, is not only linked to the more or less illustrious exiles who were confined here, but above all to the historical, political and economic events of the abbey of Santa Maria a Mare (defined by Émile Bertaux as the Montecassino in the middle of sea

According to the Tremitense Chartularium, the first religious center was built in the territory of the Adriatic islands in the 9th century by the Benedictines as a direct dependence of the abbey of Montecassino. What is certain is that in the eleventh century the abbey complex reached its maximum splendor, dramatically increasing possessions and wealth, which led to the rebuilding of the church by Abbot Alderico with consecration

in 1045 made by the bishop of Dragonara .

The magnificence of this period is testified by the presence within the walls of the monastery of illustrious guests, including Frederick of Lorraine (who later became Pope Stephen IX ) and Dauferio Epifani (later Pope Victor III ). With the bull of Alexander IV of 22 April 1256 , the consistency of the assets owned by the monastic community was confirmed. The entire complex remained a possession of the abbey of Montecassino for about a century, despite the pressing requests for autonomy and the protests of the Tremiti religious.

In the thirteenth century , now released from the Cassinese monastery, it had possessions on the mainland from the Biferno to the city of Trani . According to the chronicles of the time, the tensions never subsided with the Lazio monastery and the frequent contacts with the Dalmatians , unpopular with the Holy See , led the monks of the complex to a moral decay that led in 1237 Cardinal Raniero da Viterbo to appoint the then bishop of Termoli to replace the order of San Benedetto with the Cistercians at the leadership of the abbey.

Later, Charles I of Anjou equipped the abbey complex with fortification works. In 1334 the abbey was plundered by the Dalmatian corsair Almogavaro and his fleet, coming from the Dalmatian city of Omiš , who slaughtered the monks putting an end to the Cistercian presence in the archipelago.

In 1412 , following pressure and apostolic letters, and on the direct order of Pope Gregory XII , after the rejection of various religious orders , a small community of canons regular , coming from the rectory of Santa Maria di Frigionaia in Lucca and led by Leone da Carrara moved to the island to repopulate the ancient religious center. The Lateran people restored the abbey complex, also expanding the buildings, especially with the construction of numerous cisterns still functioning today and extended the possessions of the abbey on the Gargano, in the Land of Bari , Molise and Abruzzo .

In 1567 the abbey-fortress of San Nicola managed to resist the attacks of the fleet of Suleiman the Magnificent .

The abbey was suppressed in 1783 by King Ferdinand IV of Naples who in the same year established a penal colony on the archipelago. In the Napoleonic period the archipelago was occupied by the Murattians who entrenched themselves inside the fortress of San Nicola, validly resisting the assaults of an English fleet (year 1809 ). Of these attacks the holes of the English cannonballs on the facade of the abbey are still visible today. Following this event, Murat granted a pardon to the deportees who had collaborated in the resistance against the British. Thus it was that the first colonization of the Tremiti Islands ended, carried out through the establishment of penal colonies.

In 1843 King Ferdinand II of the Two Sicilies, with the intention of repopulating the islands, had many fishermen from Ischia settle there who were able to profitably exploit the fishiness of that maritime area and from families of the kingdom thus giving rise to a second colonization of the Tremiti .

Concentration camp of the Tremiti islands, Arab prisoners

In 1911 about 1,300 Libyans who opposed the Italian colonial occupation were confined to the Tremiti. [11] About a year later, one third of these had died of exanthematous typhus .

Municipal autonomy dates back to 1932 .

In the Fascist era the archipelago continued to be a place of confinement, including the future President of the Republic , Sandro Pertini and Amerigo Dumini .

Mussolini had hundreds of homosexuals deported to San Domino in 1938. No law prohibited homosexuality at the time, but Mussolini wanted to hide the very existence of homosexuals, claiming that "In Italy there are only real men". Conditions on the island were very difficult and some died. San Domino had the particularity of being the only internment camp where all the prisoners were gay men, paradoxically forming a gay "community" The dorms were spartan, with no electricity or running water. A bell rang at 8 in the evening every day, signaling that it was no longer allowed to stay outside.The confinement ended on May 28, 1940, by the will of the police chief Bocchini, in agreement with the duce: Italy was at war and they served men and detention spaces. On 7 June the confined left the island and, surprisingly, many of them were saddened, as they awaited their return home where, even if free, they could not be themselves because of the rampant homophobia.

In the fall of 1940, San Domino was transformed into an internment camp where anti-regime politicians and Jews were imprisoned.

In 1987 Mu'ammar Gaddafi , by virtue of the deportations of Libyan citizens carried out mainly by the Giolitti government starting from 1911 , declared that the archipelago was part of Libya . These territorial claims followed the diplomatic tension that existed with Italy.

In the night between 7 and 8 November 1987 two Swiss citizens, Jean Nater and Samuel Wampfler, planted a bomb on the San Domino lighthouse. The first was killed in the attack, the second was captured and sentenced. At first it was thought of a Libyan attack, but subsequent journalistic hypotheses suggested that the two attackers, secret agents, collaborated with the French services, a nation with which Italy at the time had a diplomatic dispute over the succession of Habib Bourghiba in Tunisia . However, the trial of the second attacker, which ended in 1990 with a sentence of ten years in prison (never granted), did not lead to any certainty.

On October 28, 2008, about thirty inhabitants of the islands voluntarily underwent a DNA test in order to establish if in their blood there was any trace of those Libyan deportees of 1911. The result was negative.