Gacka is one of the oldest Croatian provinces. Its inhabitants, the people of Gacka, are mentioned as early as in the early 9th century, for the first time in 818, at the time of the origin and formation of the early medieval Croatian state. Borna was the first Croatian ruler to subject a significant larger area to his rule. In the Latin Frankish records he was referred to as dux Guduscanorum, or leader of the people of Gacka, and the people of Gacka as natio Guduscanorum. From his home Gacka, Borna expanded his authority to Dalmatia and Liburnia.
The then European superpower Francia referred to him as dux Guduscanorum, dux Dalmatiae atque Liburniae – the Prince of the people of Gacka, Dalmatia and Liburnia. It is considered that the area of the then Gacka covered a much wider area than at the present, stretching from the Raša River in Istria to the Una River in the east. In a later period, Gacka gradually narrowed to the present area. In the mid-10th century, the Byzantine Emperor, writer and philosopher Constantine VII Porphyrogenitus mentions the Croatian counties, three of them, among others: Gacka, Lika and Krbava. They were ruled by a ban, while others were ruled by a prince. In the early 10th century Gacka thus belonged to the first Banovina of Croatia known in history.
The Prehistoric Period
The area of Gacka had been inhabited as early as in prehistoric times. The oldest site in the area of Gacka from this period is located on its southern edge in Pećina in Lešće. The traces of charred bones of wild animals and bones with clearly visible traces of stone tools reveal the presence of humans from the Mesolithic period - the transition from early to late Stone Age (10000-4000 BC). Back then, man was still a wild animal hunter.
Somewhat younger habitats and traces are found in precisely the Brinje area. The cave of Siničić špilja, on the way from Brinje to Letinac, has unveiled its secrets only recently. In it lived a Paleolithic hunter in 9500 BC (late Mesolithic period) who left the, still undeciphered, leptolithic engraved pictorial representations on the smooth rocks of the cave. A group of notches similar to Germanic runes was probably a primitive lunar calendar. Remains of pottery were also found in the cave. Man was still a hunter getting used to a sedentary way of lifestyle.
Traces from the middle and late Bronze Age were found in the area of Vrhovine. In the cave of Bezdanjača under Vatinovac hill, just two kilometers west of the Vrhovine toward Zalužnica, a necropolis from 1400 BC was discovered. The cave has two parts: at one time in prehistory, the first part below the pit vertical was used as a dwelling (later, the main settlement was on Vatinovac hill), while the other sloped greater part was used as a necropolis. With more than 250 skeletons discovered, it is one of the largest cave necropolises in Europe. Man was already breeding domesticated animals (cattle, sheep, goats, dogs) and cultivating grains. It is evident from the remains of the material culture that the group of people living in the region belonged to the Proto-Illyrians, predecessors of later Illyrian tribes.
In the late Bronze Age in the 9th and 8th centuries BC, the Illyrian tribe Iapydes occupied the entire area of Gacka and beyond. Iapydes culture was very rich and vivid, and partly differs from cultures of other Illyrian tribes. It was exactly the sites in the Gacka area where the most valuable archaeological finds of this tribe were excavated. Iapydes mostly lived in forts that were built on top of low rounded hills: in Crkvina in Kompolje (Avendo), in Veliko and Malo Vitlo in Prozor (Arupium), in Veliki and Mali Obljaj east of Vrhovine. It is considered that Brinje was Monetium. Other such forts were in Drenov Klanac, Staro Selo and Švica (as many as 23 ruins were identified only in the Gacko polje). The culture of copper processing and production of exceptionally rich jewelry (especially the jewelry made of amber and glass) has experienced a renaissance in the early Iron Age (8-5th centuries BC). In these rich findings, the beautifully processed Iapydic headgear and hats stand out. The ethnologists consider them the precursor of today's male red cap with a short fringe of the Dinaric type (some call it the cap from Lika or Gacka). Their later successors have not only taken the Iapydic cap, but other parts of the traditional male and female costumes as well. The Iapydes from the area of the present Gacka had cultural ties with Etruscans and Greeks and, across Pannonia, with cultures of the Black Sea as well.
The Roman Period
In the 2nd century BC, the Romans began to disturb the peaceful life of Iapydes. Iapydes had been at war with them for nearly two centuries with changing war luck. They were finally conquered by the Roman Emperor Octavian in 35 BC.
With the arrival of the Romans, the present area of Gacka receives on traffic importance. Along with the construction of the road from northern Italy to Greece, the Roman authorities, gradually brought changes in the life of the natives. They built, expanded and fortified Arupium in Veliko and Malo Vitlo in the present Prozor as their central settlement. According to archaeological remains, it was an important site with public buildings, pagan temples and a high standard of living for that time (underfloor heating). Arupium was a central Roman settlement in the areas of Gacka, Lika and Krbava from which they controlled the main road and the intersection to Dalmatia and Pannonia. The lively traffic activity brought a multitude of Roman soldiers to Gacka, and they brought their Roman cults with them. In the 2nd and 3rd centuries a widely spread cult of Mithras, the Sun-God, was brought from Senia (the present Senj). In terms of artistic treatment, the Mythrian shrines in Čović and Sinac are of Italic origin, while the shrine in Špilničko polje east of Otočac is of Noric-Pannonian origin.
Early Middle Ages
With the weakening of the Roman Empire, barbarian peoples started to invade Gacka. At the end of the 5th century, Goths arrived and established their short-lived authority in the area of Dalmatian Croatia. According to some sources, the name of the province of Gacka is derived from the name Goths, meaning 'small state of Goths'. After the Goths, who partly remained living in this area and mixed with the natives, in the mid-6th century came the Slavs. The Avars invaded the area at the end of the 6th century, and the Croats came in the 7th century. According to historical sources, it appears that in this difficult area in terms of climate and relief these different nations were more tolerant of each other and found a way to co-exist. Thus in the mid-10th century, Constantine VII Porphyrogenitus writes that there are still the Avars in Croatia, which differ from other people in appearance. It seems that the largest number of them is found exactly in the province of Gacka.
With the arrival of Croats to the area of Gacka, spreading their name and influence on other nations, at the time of the highest power of Francia, the then European superpower, the first nucleuses of the medieval Croatian state was created exactly in the area of Gacka. Prince Borna expanded his authority from Gacka to Dalmatia and Liburnia and created the first larger state area under the Croatian name. In the late 9th and early 10th centuries, Gacka and the neighboring Krbava and Lika are ruled by the ban. In the time of the Croatian kings, Gacka loses on importance as the central state space, which shifts to the areas of northern and central Dalmatia.
Gacka from the 13th to 16th Centuries
When Hungarian kings assumed power in Croatia, Andrew II, King of Hungary and Croatia, gave the province of Gacka to the Knights Templar in 1219. Shortly afterwards (in 1241), Gacka was devastated by the Mongols. Batu Khan broke with his hordes to Kapela to catch the Hungarian-Croatian King Bela IV. The Templars did not retain Gacka in their possession for long. King Bela took Gacka from them and exchanged it for another possession in 1269.
The late 13th century saw the emergence of the counts of Krk, the later Frankopans (Frangepanes). Gacka became their property in 1290, remaining in their possession until as late as 1468 when it was taken over by the Hungarian-Croatian King Matthias Corvinus. The Frankopans had the following fortified towns in Gacka: Otočac, Prozor, Vrhovine, Dabar, Brlog, Sokol, and Jelovik. Apart from fortifying and establishing towns and forts, they also built churches, donated monasteries, and helped develop the culture and literacy in general. Their main centers were located in Otočac and Brinje where they left the greatest trace. During the reign of Sigismund of Frankopan, in 1460, the diocese of Otočac was established. It lasted until the Ottoman invasion of 1534.
Already in the late 15th century, and then in the 16th century as well, the invasions of the Turks (Ottomans) were becoming more and more violent and dangerous. Krbava and Lika fell under their rule in 1527. Gacka and Otočac became border areas exposed to frequent Ottoman attacks. In the early 16th century, Gacka, especially the Gacko polje and the area of Vrhovine, and slightly less the area of Brinje, experienced the exodus. It was the time of the population's massive emigration and flight to the Adriatic littoral, Gorski Kotar and Carniola, as well as to northern Croatia, Hungary and Austria. The only populated areas remained were Otočac, Brinje and Prozor.
Gacka as Part of the Bulwark of Christianity
To defend from the invading Ottomans, Hungarian King Matthias Corvinus established the military captaincy of Senj in 1469. The following fortifications belonged to the captaincy in 1538: Otočac, Prozor, Brlog, Brinje, Senj, Jablanac, and Bag. In 1578, the military defense was reorganized and the Primorska krajina established. Otočac and Brinje would remain the two centennial strongholds for the defense of Gacka. Until the final expulsion of the Ottomans from Krbava and Lika in 1689, several battles were won against them in Gacka. Count Petar Zrinski defeated the Turks with the people of Otočac twice in 1655. In 1657, the soldiers from Otočac and Senj defeated an army of 6000 Turks in the Gusić polje. In 1663, with an army of 2000 soldiers, Petar Zrinski and Fran Krsto Frankopan defeated 8000 Turks near the locality of Jurjeve stijene. Thus they finally prevented further Turkish incursions into the depth of the free Croatian territory.
Immediately after the expulsion of the Turks from Krbava and Lika, where Marko Mesić, a Serbian orthodox priest from Brinj excelled in particular, the Military Frontier suffered a new reorganization. The entire area of Gacka was subjected to the authority of the Military Frontier Administration in Karlovac. With the disappearance of the Turkish threat in the late 17th century, immigrants from Gorski Kotar, Carniola and northern Dalmatian coast systematically settled the deserted area of Gacka. In 1746, the glorious regiment of Otočac was formed from the old military captaincy of Otočac. It comprised the area from the coast all the way to the east to the Bosnian border. It would last as late as until the demobilization of the Military Frontier in the 19th century. However, the repressive system of the Military Frontier, that largest barracks in whole Europe, caused discontent and rebellion of the people of Brinje in 1746. The rebellion was crushed and the rebels brutally punished. From the 18th until the mid-19th centuries, the people of Gacka took part not only in the wars with the Ottomans, defending the Austrian Empire; they had to fight for the Viennese court across Europe as well. In these wars, especially in the suppression of the Hungarian revolution in 1848, they impressed with their bravery, and were awarded respectable imperial decorations. After the demobilization of the Military Frontier in 1881, the region of Gacka joined the civilian Croatian state and lived to see the dissolution of the Austro-Hungarian Empire in 1918.
Gacka in the 20th Century
With the dissolution of the Austro-Hungarian Empire, Gacka is in the southern Slavic community for the first time. Since 1939, it is part of the Croatian Banovina. In 1941, Otočac and Vrhovine were attached to the Great County of Gacka and Lika while Brinje was part of the Great County of Vinodol and Podgorje. In World War II, the founding session of ZAVNOH, the National Anti-Fascist Council of the People's Liberation of Croatia, was held in Otočac. At the end of World War II, Otočac and Brinje became county towns and Vrhovine a municipal town.
In 1991, the people of Gacka experienced a catharsis in the war against Serbia and the local Serbian rebels. One third of the territory of Gacka in the northeast was occupied. During the violent attacks, Brinje and Otočac, and the surrounding villages in particular, suffered major destruction and many casualties. In the new territorial and administrative organization of Croatia, Otočac received the city status in 1993, while Brinje and Vrhovine once again became municipalities. The city of Otočac and the municipalities of Brinje and Vrhovine are part of Lika-Senj County.