The Chola military () was the combined armed forces of the Chola Empire organized during two separate Tamil golden ages, the Sangam Period and the Medieval Era. The Chola military fought dozens of wars, it also underwent numerous changes in structure, organization, equipment and tactics, while conserving a core of lasting Tamil traditions. Sangam period (300 BC–300 AD) It has not been possible to assemble an internal chronology of the Sangam works and pinpoint when and how the early Chola military was formed. The earliest mention of the Chola army comes from Indian historian, K. A. Nilakanta Sastri, who claimed that King Ilamchetchenni defeated Maurya Empire King Bindusara, son of Chandragupta Maurya, in battle. Fragmentary poems in the Purananuru also state that, Ilamchetchenni Chola, revered as a brave king and hard fighter, successfully resisted the exploration of the Mauryan army in Tamilakam. Karikala Chola Karikala Chola stands pre-eminent amongst all those mentioned in Pattinappaalai. 'Karikala' means 'elephant feller' or 'charred leg', which is assumed to be a reference to an accident by fire that befell the prince early in his life. Pattinappaalai describes this accident and the enterprising way in which the prince escaped and established himself on the Chola throne. Pattinappalai is a poem on the then Chola capital Kaveripattinam and describes the numerous battles Karikala fought against the Cheras and Pandyas, including the famous Battle of Venni where the Chola army defeated a confederacy of (about) a dozen rulers headed by Chera and Pandya kings. Following the battle, the Chera king was disgraced (received a wound on his back) and committed suicide. Karikala thus broke the confederacy that was formed against him, conquered the Chera and Pandya kingdoms, and established Chola hegemony over Tamilakam. After the Battle of Venni, Karikala defeated the confederacy of nine minor chieftains in the Battle of Vakaipparandalai. He also invaded Sri Lanka and took away, among other things, 12,000 Sinhalese men to work as slaves in the construction of the Kallanai Dam. The poet Kovur Kilar mentions a protracted civil war between two Chola chieftains Nalankilli and Nedunkilli. Nedunkilli isolated himself in a fort in Avur, which was being besieged by Mavalattan, Nalankilli's younger brother. The poet chided Nedunkilli to come out and fight like a man instead of causing untold misery to the people of the city. In another poem, the poet begs both the princes to give up the civil war