The Cerna River loop is a region that stretches west of Pelagonia on the territory of Mariovo, between the Cerna River and the villages of Brod, Rapes, Grunishta, Staravina and Gradeshnica. In the history of the First World War, this region was a place of fierce battles, from October 1916 until the end of the war in September 1918, mainly between the French and Serbian armies on the one hand, and Bulgarian armies on the other. Occasionally, Italian, Russian and German troops participated. The first fighting took place at the time of the Allied counter-attack in October 1916. The first Serbian troops managed to cross the Cerna River in the night of 4-5 October, east of the village of Dobroveni. Two days later, they also crossed the river near the village of Skocivir.
In the following days, all Serbian attempts along the front line near the villages of Brod, Dobroveni and Skocivir were unsuccessful. The Serbian army did not achieve any further success until ten days later, when they managed to retain the Bulgarian army a few kilometres to the north. At the same time, the Bulgarian armies, assisted by the Germans, tried unsuccessfully to overthrow the opponent on the other side of the Cerna River. A significant and remarkable success in this part of the Front took place in November, after a strong artillery offensive: after three days of continuous artillery fire, the Bulgarian troops were forced to leave their positions and the front line gradually moved north. Until 6 November, the losses of Bulgarian forces were considerable and many were captured.
The advancement of the Serbian armies led to the loss of the very important heights 1212 and 1378; they dominated the terrain and were crucial for the defence of Bitola. As a result of the fighting in the Cerna River loop until 18 November, the Serbian armies succeeded in retaining the Bulgarian armies on the Kota 1050 line, the villages of Makovo, Zovik and Gradeshnica. This allowed Allied control over most of the Cerna loop. On 19 November, the French army entered Bitola. The following days, the Serbian and French armies managed to take only part of the Kota 1050 on Mount Selecka, which gave an excellent overview of Pelagonia, after which the front line stabilized along Karaman village, Kota 1050, the villages of Makovo, Zovik, Gradeshnica. The battles in this part of the Front continued the following year until May 1917.
This battle is part of the Allies' spring offensive with the aim of involving the armies of the Central Powers as much as possible in the attacks on the major fronts of the Entente (France and Belgium). Initially scheduled for April, and due to bad weather conditions, General Sarrail postponed the offensive until May. The Allies' offensive in the Cerna loop was to be carried out by French, Italian and Russian troops. The objective was to break through enemy lines and penetrate Prilep, which would have jeopardized the background of the Bulgarian and German armies in the vicinity of Bitola. The attack began on 5 May with artillery preparation, although the infantry began to move three days later, on 8 May. The German and Bulgarian soldiers were very well established and managed to repel the initial attacks. The Allies attempted new frontal attacks to break through the lines of the Front on 11 and 17 May, but unsuccessfully.
In some parts of the Front fighting took place in the trenches, face to face. It was only after the failed operations in the vicinity of Bitola and Dojran that General Sarrail decided to end the offensive in the Cerna River area and along the Front Line from 21 to 23 May. Losses were significant on both sides. The Allies had more than 5,000 soldiers killed or wounded, representing about 40% of the total casualties since the beginning of the year. On the other hand, German-Bulgarian forces also suffered heavy losses. The Bulgarian armies alone numbered more than 1,600 dead and wounded soldiers. A few months later, in October, the central forces tried four times to penetrate the Cerna loop, but unsuccessfully. In the following months and during 1918, this part of the Front did not experience any other major battles, only daily artillery fire on the Front Line.