The Chakravyūha or Padmavyūha, is a multi-tier defensive formation that looks like a blooming lotus (padma, पद्म) or disc (chakra, चक्र) when viewed from above. The warriors at each interleaving position would be in an increasingly tough position to fight. The formation was used in the battle of Kurukshetra by Dronacharya, who became commander-in-chief of the Kaurava army after the fall of Bhishma Pitamaha.
The various vyūhas (military formations) were studied by the Kauravas and Pandavas alike. Most of them can be beaten using a counter-measure targeted specifically against that formation. It is important to observe that in the form of battle described in Mahabharata, it was important to place the powerful fighters in those positions where they could inflict the maximum damage to the opposing force, or defend their own side.
The Chakravyūha or Padmavyūha was a special formation (Vyuha), and knowledge of how to penetrate it was limited to only a handful of warriors on the Pandavas' side: namely Abhimanyu, Arjuna, Krishna and Pradyumna, of which only Abhimanyu was present at the most-famous occasion of its use. Because he had never learnt to escape the formation, he was trapped upon entry and fought alone. After Abhimanyu had penetrated the sixth tier of the formation, all the Kauravas' commanders attacked him simultaneously, against the righteous rules of warfare Dharmayuddha, and gradually exhausted and killed him.