While the main army led by the Bavarian Elector Maximilian II Emanuel marched against the castle, Count Louis of Baden (the „Türkenlouis”) joined forces with the Croatian army of Bán (Duke) Erdődy II Miklós and they were marching along the Száva River.

The Count arrived in Eszék (Osiek) in the middle of July where the Transylvanian army joined him. Then, they moved towards Pozsega where the troops of Colonel Lorenz von Hoffkirchen joined in. They set out towards Sziszek castle and reached it on 7 August. He met Erdődy and his 4,000 soldiers at Petrinja.

In the meantime, Pasha Sziavusz of Bosnia either had the crossing places over the Una River destroyed or reinforced the fords but it could not stop Louis of Baden who forced his army through the river near Kosztajnica on 13 August. Pasha Sziavusz decided to withdraw his troops so Kosztajnica fell to the Christians the next day. Then, Dubica was also taken and Gradiska fell on 21 August.

The troops of the Count continued their advance on the southern bank of the Száva (Sava) River. They reached Brod on 28 August and the Count had the town reinforced and turned it into a strong bridgehead in order to guard his supply lines. During this time, the units of Pasha Sziavusz made a camp at Derventa. Louis of Baden decided to make a surprise attack so he had the fake news spread that he would return to Slavonia.

The Pasha didn’t want to miss the opportunity, and his scouting cavalrymen soon appeared around the Christian camp. The Count left behind the supply wagons and his infantry and set out against the army of the Pasha on the night of 5 September. When he arrived, it was he who was surprised, seeing that the Pasha had 15,000 soldiers and not just 7,000. Moreover, the enemy was expecting him, the Ottoman army stood on higher ground.

The Count had to decide whether to attack or retreat but the latter would have been a dangerous move and he didn’t like retreating, anyway. He made a quick decision and assaulted the enemy from march, in spite of being outnumbered 5 to 1. He took his cavalry through a pass but his vanguard was immediately ambushed by the Ottoman horsemen. As the Imperial troops were tired because of the night march, they were slowly overwhelmed by the Turks.

In the critical moment, the unit of Major General Count Friedrich Magnus zu Castell appeared on the battlefield and attacked the enemy in the side. The Ottoman cavalry fled and the Imperials began to chase them at once and ran headlong into the Janissaries.

Bloody close combat got developed and the steady Janissary troops have all been slaughtered. There were 5,000 of them killed and 2,000 were taken. As for the Christian cavalry, only 200 of them were mortally wounded in the Battle of Derventa.

After the victory, Count Louis of Baden returned to Brod where the reinforcement sent by Maximilian Emanuel had arrived, too.

The Count decided to go on and take Zvornik town but the crossing places of the Drina River had been blocked by the Pasha. Despite this, the Count broke through these blockades and marched into the town abandoned by the Pasha, on 25 September.

As for him, these most successful fights have been ended for this year and Count Louis of Baden returned to Vienna.

(The source given by Szibler Gábor: „Bagi Zoltán Péter: Türkenlouis. Badeni Lajos (1655-1707). Pécs-Budapest, 2019.”)