On the steep cliffs of the gorge between Kozjak and Mosor stands the Klis fortress with one window facing the sea and the other facing Zagora. It was built on an extraordinary strategic location that enables military and trade control over the entire Kliško field and the area of Salona and Split. Due to its importance, Klis was often called the key to Dalmatia and the heart of the medieval Croatian kingdom
The first traces of the population of the area around the Kliška fortress date back to the Late Stone Age, as indicated by the archaeological finds from the Krčina cave, which is associated with the impresso culture. It is the first Neolithic culture on the Adriatic that lasted from 6000 to 4500 BC. Kr., And is characterized by the production of ceramic dishes in which various shapes were pressed before baking. We do not know much about the then population of this area today, but archaeological findings suggest that in the later stages of the impresso culture, agriculture appeared on the Adriatic coastal area.
In the following period there is no reason to doubt that this area was inhabited, and the first population we can accurately identify are the Dalmatians, one of the Illyrian tribes. They inhabited the area from the river Krka to the Neretva, including the area along the river Jadro (today's Solinčica). Illyrian forts were built on natural elevations for easier defense against possible invaders. At the foot of the Kliška fortress, the remains of one such settlement were found, whose role was to control the pass between Kozjak and Mosor. Together with the Marquez beam and the hillfort above Odž, which are located further north on the Kozjak hill, this hillfort controlled access to the Illyrian Salona and the mouth of the river Jadro. This role will be taken over by all later buildings on a given location.
With the spread of the Romans came contacts and eventually conflict between the native Illyrian population and the conquerors of Lazio. After the protracted wars waged by the Illyrian uprisings, they were finally reconciled by the suppression of Baton's uprising in 9 AD. In the late Roman period, the Roman fortress of Kleis was founded, in which a military crew resided as a outpost of Salona, the ancient metropolis of Roman Dalmatia.
With the fall of the Roman Empire, the area of Salona and the fortress of Klis came under the rule of the Byzantine Empire, in whose hands it would remain until the arrival of new conquerors from the northeast. The guard above Salona finally, according to Constantine Porphyrogenitus in his work De administrando imperii , knelt down in 614. Then, allegedly by deception, an Avar-Slavic horde passed through the fort, which will continue to plunder and destroy Salona, whose population will take refuge behind the walls of Diocletian's Palace, the core of today's Split.
In the next 200 years, there are only scarce data, primarily due to the large turbulences that occur in that period and the lack of literacy among the newly settled population. Then Croats came to this area, and it is very likely that they saw the Adriatic Sea for the first time from Klis, because it is assumed that they descended from Pannonia by the old Roman road that led from the Danube through Bosnia to Salona. The next great moment in the history of the Klis fortress is Trpimir's charter from 852, in which it is mentioned that Klis is one of the prince's estates. For the next seven centuries, the fortress changed its owners, and stood out during the Tatar invasion of the Hungarian-Croatian kingdom when it provided refuge to King Bela IV. in front of the Horde.
Nevertheless, Klis experienced its significance for Croatian history from the 15th century onwards, when it would find itself at the crossroads of three empires - the Ottoman Empire, the Venetian Republic and the Habsburg Monarchy. At that time, Uskoks were operating in Klis, military units that got their name because of their "jumping" into enemy territory that would be looted and returned to the base. The leader of the Klis Uskoks was Petar Kružić, who with his men defended the fortress from the much more powerful Ottoman army for more than twenty years. However, with very scarce help from the rulers, Klis could not resist forever and in 1537 it fell into Turkish hands.
For the next 111 years Klis will be in the hands of the Ottomans. During this period, the Venetians or Uskoks tried to capture it several times, and in 1596 they even succeeded in their plan. About a hundred Croats, led by Split nobles, raided the fortress, after which more compatriots from the surrounding area rushed to their aid. However, the same year was followed by a counterattack by the Ottomans who eventually with a several times larger army forced the defenders of the fortress to leave their positions and leave the city.
Klis Fortress played its last major military role during the Candian War between the Venetian Republic and the Ottoman Empire. At that time, great battles were fought for the fortress, which eventually fell into the hands of the Venetian army, under whose flags many Croats fought. From that moment on, Klis would no longer see major military actions under its walls - it remained in Venetian hands until 1797, when it came under French rule. With the fall of Napoleon, the fortress became part of the Habsburg Monarchy, and with its abolition it shared the fate of Croatian territory until 1990, when the flag of the Republic of Croatia was developed on it.
