The rich history of the Gacka valley is presented from the settlement by the Illyrian tribe of Iapodes, with its valuable indigenous culture, through to the Roman period when the Iapodes came under Roman rule, with Romans leaving valuable Mithraic stone monuments (altars in Špiljničko Polje and Rajanov Grič in Čovići). The historical outline continues with an explanation of the term Gacka which is mentioned as a province as early as the 9th century, with the inhabitants of Gacka first mentioned in 818 during the rule of King Borna, the time of formation of the Croatian medieval state.
The first written mention of Otočac is on Baška Tablet, one of the most important written records in Croatian Glagolitic script dating back to around 1100 AD. The name Otočac probably derives from the fact that Otočac was located on a natural island in the middle of the Gacka river, surrounded with fortification walls and towers for protection, as shown in the displayed 17th century town plans. The oldest preserved deed of donation mentioning Otočac is the one dating back to 1300 AD whereby King Charles II of Naples grants the lands together with the town of Otočac to Doimus II, the Prince of Krk, as confirmed by King Roberto in his charter of 1316 in which Otočac is called a town (castrum). On 5th March 1460, during the rule of Sigismund Frankopan, Pope Pius II founded the Otočac diocese and upgraded the church of St. Nicholas to a cathedral, with Otočac granted the status of a town (civitas). The diocese ceased to exist in 1534. At the end of the 15th and throughout the 16th centuries the Lika and Krbava regions became subject to Ottoman invasions and fell under Turkish rule in 1527, however, Otočac remained invincible. In defence against the Ottoman attacks several fortified towns were built near Otočac: Dabar, Prozor. Gusić Grad, Karin Grad, Šimšanovka Kula. The Turks suffered several severe defeats in the Gacka valley. The first victory over the Ottoman army took place on the river Gacka in 1467, followed by the victory of Banus Petar on 10th May 1520 at the very entrance to Otočac. The Turks suffered another severe defeat in 1527, at Osmanagino Polje near Dabar. The town of Otočac gained in importance in 1543 with Banus Petar Keglević’s defeat of the Turkish troops near Otočac. In 1578, the Military Border defence was reorganized and Otočac became part of the newly established military frontier district of Primorje. Until the final expulsion of the Turks from the Lika and Krbava regions in 1689, a number of successful battles were fought in the Gacka valley. Count Petar Zrinski, with the assistance of the Otočac population, defeated the Turks twice in 1655 and in 1657 Otočac and Senj inflicted a defeat on 6000 Turkish troops in Gusić Polje. The glorious victory of Petar Zrinski and Fran Krsto Frankopan took place on 16th October 1663 near Jurjeve Stijene when their army of 2000 men defeated a Turkish army of 8000.
Otočac belonged to the Military Frontier (border) from the 15th century to its abolition in 1881. In 1746, the old Otočac Captaincy was formed into the Otočac regiment. During this period Otočac prospered becoming an important military, cultural and trading centre. The Empress Maria Theresa made Otočac into a trading station and a military magistrate was introduced there. Since 13th September 1746, weekly fairs had been held in Otočac on Wednesdays. The so-called trivial school for the Military Frontier officers’ children was set up in 1727. A big school building was built in 1782, and in 1805 the girls’ school started in Otočac. In 1871, Croatian language was introduces as a subject in the school curriculum. In 1888, a four-year higher-grade elementary school of trades was introduced. After the World War I this school was turned into a state public school, and in 1925 into a lower-grade grammar school. In 1844, a small theatre group was founded in Otočac under the patronage of army general Nikole Maštrovića. The group had two performances in the Croatian language.
Otočac got its volunteer fire department in 1868, the third oldest volunteer fire service to be established in Croatia. In 1873, a public library was opened. The first movie was shown in 1902, and since 1907 Otočac has had a sports association - "Sokol". Otočac also has a long tradition in health care dating back to the Military Frontier period. In 1836, a massive hospital was built underneath the Fortica hill where a fortress was erected in 1619 for protection against the Turks.
Between the two world wars, trades flourished in Otočac, making the town into a strong trading and cultural centre in the Lika region. During World War II, in 1943 ,Otočac became a stronghold of the Croatian anti-fascist movement. On 13th June 1943, the first ZAVNOH meeting was held with Vladimir Nazor nominated president. ZAVNOH (the National Anti-Fascist Council of the People’s Liberation of Croatia) was the highest political and representative body of the Croatian anti-fascist forces. After the end of the second world war Otočac began to develop into an industrial town with wood-processing, chemical, leather-processing, metal-processing, civil engineering, transport and other branches of industry.
The display ends with an outline of events of the 1991 War of Independence when Otočac suffered enormous human and economic losses.