| Conflict: | Battle of Kajmakčalan |
| Partof: | the Serbian Campaign of the Balkans Theatre of World War I |
| Date: | 12–30 September 1916 |
| Place: | Kajmakčalan |
| Result: | Serbian victory[1] |
| Commander1: | Živojin Mišić |
| Commander2: | Kliment Boyadzhiev |
| Strength1: | 1st Army with main effort by Drina Division |
| Strength2: | 1st brigade of 3rd "Balkan" Infantry Division with the main effort by 11th "Sliven" Regiment |
| Casualties1: | 4,643 casualties[2] of which belonging to the Drina Division |
| Casualties2: |
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The Battle of Kaymakchalan was fought between Serbian and Bulgarian troops on the Macedonian front during World War I.
The battle was fought between 12 and 30 September 1916, when the Serbian army managed to capture the peak of Prophet Elijah while pushing the Bulgarians towards the town of Mariovo, where the latter formed new defensive lines. Between 26 and 30 September, the peak changed hands several times until the Serbian army decisively captured it on the 30th.
The battle proved to be very costly for both sides. Serbian losses had reached around 10,000 killed and wounded by 23 September. The Bulgarian companies had been reduced to 90 men each, and one regiment, the 11th Sliven Regiment, had 73 officers and 3,000 men hors de combat.
From a strategic standpoint, the battle was not a significant success for the Allies due to the upcoming winter that rendered further military engagements almost impossible.
Today, there is a small church on the peak of Prophet Elijah where the skulls of dead Serbian soldiers are stored, and it is regarded as a cultural site and is a tourist attraction. There is confusion about the name of the church, but it is called Saint Peter's (Sveti Petar in Serbian), which stands on the peak called Prophet Elijah.[3]