The knights of St. John of Jerusalem, also known as the Hospitallers, were originally an association of charitable brotherhoods who were assigned in 1048 to a hospital in Jerusalem that catered to western pilgrims flocking to the church of the Holy Sepulcher.They later came also to be known as the “knights of Rhodes”, and still later as the Knights of Malta.

Soon after establishing themselves in Palestine they became a religious order under the “patriarchate of Jerusalem”. In time they assumed a military purpose and character, attracting knights from around western Europe who were sworn to protecting the Holy Sepulchre and resisting Muslim advances.

The hospitallers were forced to relocate to the city of Acre on the coast of Palestine after Saladin captured Jerusalem in 1191, but came into conflict with another western force, the knights Templars. In 1291 the hospitallers were besieged by the Templars and forced to move to Cyprus, and then in 1306 to Rhodes. After numerous unsuccessful request to be given command of Rhodes by Genoese, the knights besieged the island’s capital city and captured it in 1309.

Nisyros fell under the protection of the Hospitallers in 1306, when the Genoese Zaccaria family ceded Cos to them, but the knights did not take possession until 1315, after they had established themselves in Rhodes.
Because they were ceaselessly engaged in campaigns elsewhere, they entrusted the fortification and feudal administration of the island to a succession of other knights, who in return made concessions to the “Grand Magistrate of Rhodes”

These western european strongmen and their troops were kept continually busy by marauding pirates and corsairs.
During this period the fortified mountain villages of Emporios and Nokia were already established, while Mandraki prospered under the protection if its strong castle.
The knights extended the existing country road and byzantine forts, establishing a network of castles that guarded the entire perimeter of the island.
These were Mandraki, Pandoniki at Emporios, the fort at Parletia on the road between Emporios and Nikia, and Nokia, possibly the walled monastery of Stavros, which the Florentine monk Buondelmonti, who visited Nisyros in 1406, called “Argos”.

A small medieval fort is erroneously said to exist at Agios Dimitrios above the site called “Drakospilio”(dragon cave), on the southern tip of Cape Lefkos(199); the ruins are in fact greco-roman and probably belong to an ancient watch tower.
The knights also kept vigil, like the ancient Greeks before them, by way of watch towers, which were used to relay light signals by night and smoke signals by day.

Of the known forts there is a little documentation as yet; much would be gained even by the most rudimentary surveys of the structures. The most impressive and better preserved of these is certainly the “Enetikon” at Mandraki within which sits the monastery of the Panagia Spiliani. This complex is fairly characteristic of forts put up in the region by the knights of st. John, with tall tracery made of smallish squared-off stones, sometimes alternating with layers of terracotta tiles or flat stones, held together with a strong mixture of lime mortar.

There are the usual portholes and slit windows for small arms fire, marble crests and insignia, and easy to defend covered passages guarding the ascent.

Because this fort, like the others on the island, was not significantly upgraded by the Ottomans, the cannon ports and platforms that came into use after the late 15th century are few, and are likely to have been added by the knights before their surrendered in 1522.The walls and the bastions at Stravros, Nikia, and Emporios have just about vanished, through the precise circuit of the latter can still be traced.

The fort of Parletia(200) commanded the most impressive site on the island, but has tended to be overlooked by visitors. It occupies the highest point on a spectacular rock hill that sits inside the larger volcanic caldera between Nikia and Emporios.(201)The remains, which can be reached taking the footpath from Nikia beyond the monastery of Agios Iohannis Theologos, are few and hard to discern; fortification walls to have been built only on the south-east side of the hill, facing Nikia, the rest of the site being naturally defensible on account of its steepness.

A large stonebuilt cistern is visible within the enclosure, its northern side making use of the natural rock, and the whole interior showing evidence of plastering.

At the summit of the hill are the remains of a small west facing christian chapel with a solitary column of red stone and roughlyhewn bell capital; its entrance appears to have made use of an opening between two natural vertical stones, one of which has broken and fallen inwards.

Most of the original fortification walls have fallen down the slope into the lower terraces. A large fallen section shows clearly its careful construction with medium and small sized stones set in lime mortar. These original walls are consistently about one meter wide; one short strecht consists of alternating courses of mediumsized and flat stones.

Along the length of the fallen stretch of wall, thick rubble walls were subsequently erected, apparently in some haste.These are clearly defensive in nature, as they do not serve to retain earth like the terrace walls below the fort, but rise about one meter above ground on their inner side.

Though it is unclear as to whether the fallen walls collapsed due to poor foundations or as result of assault, the impression one is left with at Parletia is of a temporary fort probably put up by troops in immediate anticipation of conflict.
According to a local legend the site was a meeting place of the knights of St. John, thus give rise to the place name, which appears to be derived from Frankish word for speaking. It is also possible they the word records an agreement or treaty of the sort that is typically reached between opposed armies following a determined defensive stand by one side.

The transformation of Nisyros by the knights into a tributary feudal state in the hands of a succession of western aristocrats offered, on the one hand protection from piracy, on the order it reduced the Greek citizens into subjects of foreigners different culture and language, who were insensitive to their needs and customs. The heavy handedness of feudal lords is apparent in the record of a popular insurrection in 1352 against the italian master of Nisyros Novello Manocca da Ischia, whom the Nisyrians refused to pay their taxes to and even attempted to kill(202).

Despite the conquest of Nisyros by the knights in 1315 Ad, their abolition of the Greek Orthodox Bishopry in 1318, byzantine art, architecture, and customs remained firmly rooted on the Greek island, the population of which clung steadfastly to its orthodox faith. In a report to the Pope in 1435, “the Grand Master of Rhodes asked the priests sent to the newly established roman Catholic bishopry of Nisyros understand and speak Greek. (203)

Some Greeks and natives of mixed Greek and Frankish background are known to have adopted catholicism, though no catholics remained on Nisyros after the conquest by the ottomans. According to one account, Pope Alexander V(1409-1412, actually antipope, as his papacy was ultimately not acknowledged by the catholic church) was a Nisyrian by the name of Petros Filargis, who after growing up as an orphan beggarboy in Crete, joined the Franciscan order(204)