Due to its location on a pass that separates the mountains Mosor and Kozjak, the fortress served as a major source of defense in Dalmatia, especially against the Ottoman Empire.

Excluding the brief possession by the forces of Bosnian King, Tvrtko I, the fortress remained in Hungaro-Croatian hands for the next several hundred years, until the 16th century.

Croatian captain Petar Kružić led the defense of the fortress against a Turkish invasion and siege that lasted for more than a quarter of a century.

During this defense, as Kružić and his soldiers fought without allies against the Turks, the military faction of Uskoks was formed, which later became famous as an elite Croatian militant sect.

Today, Klis Fortress contains a museum where visitors to this historic military structure can see an array of arms, armor, and traditional uniforms.

The fortress is located above the village of Klis, 11 kilometres (6.8 mi) from the Adriatic Sea, on a pass that separates the mountains Mosor and Kozjak, at the altitude of 360 metres (1,180 ft), northeast of Split in Croatia.

[3] Perched on an isolated rocky eminence, inaccessible on three sides, the fortress overlooks Split, the ancient Roman settlement of Salona, Solin, Kaštela and Trogir, and most of the central Dalmatian islands.

[3] The ancient Illyrian tribe of the Dalmatae, who held a stronghold on this spot, are the first known inhabitants to have lived on the site of today's Klis Fortress.

[9] While describing the Roman settlement of Salona, Constantine VII speaks of the stronghold, which may have been designed or improved, to prevent attacks on the coastal cities and roads by Slavs.

[3] Relations with the Byzantines greatly improved under the Croatian duke Trpimir I, who moved the dux's main residence from Nin to Klis.

The reign of Mislav's successor Trpimir I, is significant for spreading Christianity in the medieval Croatian state, and for the first mention of the name "Croats" in domestic documents.

[18] During his participation in the Fifth Crusade, he appointed Pontius de Cruce, Master of the Order in the Hungarian Kingdom, as a regent in Croatia and Dalmatia.

[20] The Mongols attacked the Dalmatian cities for the next few years but eventually withdrew without major success, as the mountainous terrain and distance were not suitable for their style of warfare.

[22] Ladislaus IV died in 1290 leaving no sons, and a civil war between rival candidates, pro-Hungarian Andrew III of Hungary, and pro-Croatian Charles Martel of Anjou, started.

[23] During this struggle over the throne, George I Šubić of Bribir, Ban Paul's brother went to Italy, visiting the pope and the Naples court.

[26] The fortress stands along the route by which the Ottomans could penetrate the mountain barrier separating the coastal lowlands from around Split, from Turkish-held Bosnia.

[26] Although nominally accepting the sovereignty of the Habsburg king Ferdinand who had obtained the Croatian crown in 1527,[Note 2] Kružić and his freebooting Uskoks were a law unto themselves.

[28] There were about 3,000 infantry in the reinforcements, which made a sizeable relief force, that were commanded by Petar Kružić, Niccolo dalla Torre, and a papal commissioner Jacomo Dalmoro d'Arbe.

[28] After Ibrahim's death, Suleiman the Magnificent sent 8,000 men under the command of Murat-beg Tardić (Amurat Vaivoda), a Croatian renegade who had been born in Šibenik, to go and lay siege to Klis fortress (Clissa), and fight against Petar Kružić.

[30] Badly-drilled reinforcements sent by the Habsburgs fled in fear of the Turks, and their attempts to re-board their boats at Solin bay caused many vessels to sink.

[30] After Petar Kružić's death, and with a lack of water supplies, the Klis defenders finally surrendered to the Ottomans in exchange for their freedom, on March 12, 1537.

[5] During the Ottoman wars in Europe, Klis Fortress was, for a century, an administrative centre or sanjak (Kilis Sancağı) of the Bosnia Eyalet.

[5] On April 7, 1596, Split noblemen Ivan Alberti and Nikola Cindro, along with Uskoci, Poljičani, and Kaštelani irregulars, organized an occupation of Klis.

[5] From the well-fortified position in the Klis Fortress, the Turks were a constant threat to the Venetians and to the local Croatian population in the surrounding area.

[32] The Ottomans built a stone mosque with a dome and a minaret on the foundations of an earlier Old Croatian Catholic chapel[33] inside the Klis fortress shortly after they had conquered it.

After the Venetians had conquered the fortress from the Ottomans, they destroyed the minaret and converted the mosque into a Roman Catholic church, dedicated to St. Vitus (Croatian: Crkva St.

[30] "Položaj maggiore" or "Grand position" is a mixed Croatian-Italian term, dating from the time when Leonardo Foscolo captured the fortress for the Venetians in 1648.

[3] On the southwest side of the fortress, and below it, was a resort (part of the modern village of Klis) called "borgo" or "suburbium", surrounded by double walls with 100–200 towers.

[3] A similar but smaller resort (also part of modern village of Klis) existed below Mount Greben on a plateau called Megdan.

[3] The "House of Dux", later called governor's residence, was rebuilt in the mid-17th century on the foundations of the oldest buildings from the period of the Croatian kings.