During World War I, in September 1916, the Battle of Kajmakčalan between Serbian and Bulgarian troops took place at Kajmakčalan and around the adjacent peaks, resulting in a Serbian victory. There is a small church and crypt for the Serbian soldiers who died in the battle. Near the top of the mountain, on the Greek side, there is a small church named Saint Peters (Sveti Petar in Serbian), the peak itself is called, besides Kajmakčalan, Profitis Ilias ().