Chitrasena, a character in the Indian epic Mahabharata, was a Gandharva king who taught song and dance to Arjuna. He used to reside in Indra's palace along with his fellow Gandharvas and Apsaras. He also routed the army of Duryodana in a battle that took place before the Kurukshetra War.
As Arjuna's teacher
Chitrasena was introduced in the epic in the Vana Parva, as a teacher of music by Indra. Indra foresaw that Arjuna would have to spend one year at King Virata's palace as a eunuch, during which time he would need the knowledge of music and dance. He wanted Arjuna to be trained by the king of the Gandharvas, Chitrasena. Chitrasena began his classes soon and the two also became good friends.
When Urvashi cursed Arjuna to remain a eunuch for life, it was Chitrasena along with Indra who mediated with her to reduce the tenure of her curse to a single year. Chitrasena was able to achieve this by narrating to her the story of the Pandavas and the bravery of Arjuna.
Skirmish with Kauravas
In another incident in the Mahabharata, in Vana Parva, Duryodhana and his 100 brothers, accompanied by Shakuni, with a medium-sized army, were camping at the Dwaitavana in order to track down the Pandavas and jeer at them during their exile. They reached the forest and were taken in by its splendour. Duryodhana planned to swim in the beautiful lakes of the forest. But Chitrasena was already camping there along with his huge Gandharva army as per the instructions of Lord Indra to seize the Kauravas (Indra knew about Duryodhana's plan of mocking the Pandavas, so he did this in retaliation).
Duryodhana was enraged when Chitrasena's soldiers denied him an entry into the beautiful lakes of the Dwaitavana. He gathered his army and launched a savage attack on the Gandharvas. Eventually, Chitrasena made Duryodhana his prisoner.
Some soldiers went to the place where the Pandavas were residing and requested them to free Duryodhana. Yudhishthira ordered his brothers to rescue Duryodhana from the Gandharvas. The other four Pandavas reluctantly hurried off and fought with Chitrasena's army, with Arjun fighting Chitrasena. Arjuna after getting the upper hand requested Chitrasena to release Duryodhana. On his request, Chitrasena released Duryodhana. Arjuna also introduced Chitrasena as his dance teacher to his brothers.
Duryodhana was so embarrassed by this incident that he wanted to commit suicide, but was stopped by the Danavas, who assured Duryodhana about his victory in the upcoming great war against the Pandavas.