With the arrival of Hasan-paša Predojević as the Beylerbey of the Bosnia Eyalet in 1591, a period of peace established between Emperor Rudolf II and Sultan Murad III ended and the provincial Ottoman armies launched an offensive on Croatia.

Thomas Erdődy, the Ban of Croatia, used available resources and soldiers to protect the border towns, but the Ottomans managed to take several smaller forts in 1591.

As the offensive gained pace, the Croatian Parliament passed a law to permit a general uprising in the country on 5 January 1592 for fighting the Ottomans.

In early June 1592, Hasan Pasha led his troops towards Bihać, which was defended by around 500 soldiers and commanded by Captain Joseph von Lamberg.

Although under the terms of the surrender its citizens were to be allowed to leave or remain in the city without harm, more than 2,000 civilians were killed and 800 were taken captive after Hasan Pasha's troops entered Bihać.

The offensive lasted until June 1593 when Hasan Pasha was killed in the Battle of Sisak, which was the cause for the Long Turkish War (1593-1606).

[8] Ottoman authorities settled Vlachs, mainly of Orthodox faith, on the conquered territory and used them as auxiliary units in their wars.

[5] In 1578, Archduke Charles II decided to respond to Ottoman attacks with an offensive to push the frontier back to the Una River.

[13] In 1528[14] Bihać became a center of a captaincy due to its position near the border with the Ottoman Empire and a relatively large number of residents.

Many of its citizens fled the city and there was a large influx of refugees into Bihać from nearby places that were conquered by the Ottomans.

A decision was made to complete the work on Fort Brest near Sisak and the construction of a new tower in Šišinec on the Kupa River.

[17][18] As the country was affected by a drought in the summer, the rivers were drained which made it easier for Ottoman forces to cross into Croatian territory.

[17] Ferhad Pasha Sokolović, the Beylerbey of the Bosnia Eyalet, prepared an army for an attack on Bihać and its surrounding forts.

The defenders of the town, commanded by Captain Franz Horner, used their artillery and inflicted heavy losses on the Ottomans, forcing Ferhad Pasha to lift the siege on the following day.

Upon hearing of the siege of Sisak, Ban Thomas Erdődy sent help to the city and Hasan Pasha was forced to retreat on 11 August.

[23][24] This angered Hasan Pasha and he requested the High Porte to cancel the truce and declare war on the Habsburg Monarchy.

[1] In early June, Hasan Predojević raised an army and headed to Bihać with 5,000 soldiers and a large number of cannons.

Hasan Pasha detached a part of them to capture Izačić, the last remaining Christian-held settlement between Bihać and the Korana River.

[31] To keep up the morale of his troops and Bihać's citizens, Lamberg organized a public oath on 13 June where they pledged to defend the city to the last man.

[32] By the end of 13 June, Bihać was completely surrounded and Lamberg could not send couriers past the Ottoman lines.

As the first siege ladders reached the walls, Bihać's judges and councilors asked Lamberg to start negotiations with Hasan Pasha, saying that the defenders were too weak to withstand the assault and there were no reinforcements.

As they reached Mečevićev Brod (near Vaganac on the Korana river), this turned into an all-out scuffle between two parties and most of the Christians were killed in the end.

The Habsburg imperial envoy in Istanbul protested the cruelty of Hasan Paša's forces and in the name of the Emperor asked for the return of Bihać.

The Ottomans responded that "every reasonable person can figure out that Bihać can not be returned", as a mosque had already been built in the city and prayers for the Padishah were being held.

[37] It was the last Croatian stronghold in the south and with its fall the defensive line moved north and extended from Ogulin, through Karlovac and along the Kupa River to Sisak.