In 1876, Serbian forces suffered heavy losses and defeats when they tried to invade southern Bosnia who defended themselves, led by Mehmed Ali Pasha.
Cited:

“Serbian Invasion of Southern Bosnia. On the 7th, the following was published in Belgrade by the Western Army: Today, from 10 a.m. to 5 p.m., a fierce battle took place near Javor Planina on the Drina River, eight meters south of Zwornik, on the direct line between Serajewo and the Serbs. General Bach crossed the border. After a three-quarter-hour march, a clash with the enemy occurred.
The number of wounded on both sides is very high. They could not repulse the enemy, who was well positioned on a hill behind entrenchments. The battle remained inconclusive. This inconsistency is merely a cover for the Serbian defeat. The Turks, under Mehemed Ali Pasha (a Prussian convert to Islam), were in a very favorable position.
The Serbs attempted to storm the front several times but were driven back to the Serbian border after five hours. They suffered a loss of 1,500 men. The troops captured 476 breech-loading rifles, 40 ammunition carts, and shovels. The Serbian side contributed 24 battalions and 18 cannons to the battle, and it was in the Serbs’ plan to capture it and from there unite with the Negroes.
The Governor of Bosnia gave orders to also arm the Roma against the insurgents and Serbian allies. A Serbian corps under the command of Czolak Antic crossed the border at Raschka (Raschka River) near Novibazar on the 7th. A furious battle ensued immediately and continued until 1 p.m. The Turks were driven from their positions by the Serbs.
Border guard posts and blockhouses were stormed, and the line from Raschka to Novibazar was taken by the Turks. The mountain artillery, according to the Belgian report, proved itself excellently. We captured horses and trumpets, nothing else. Reports indicate that this Serbian corps, led by Ducic, was again driven out. Further south, another corps was fighting in the Jbar Valley.”
Source
Der Freimüthige Politisches Volksblatt für Jederman. Gegründet im Jahre 1862. Vienna, January 1, 1876. Nr. 1
