Arjuna held Jayadratha responsible for Abhimanyu’s death on the 13th day of the war. He vowed to kill him the very next day before sunset, failing which he would kill himself by jumping in a pyre. The Kauravas hid Jayadratha from Arjuna in a formation, knowing that Arjuna’s death would result in a Kaurava victory. However, Krishna created an artificial eclipse by using his Sudarshana Chakra to hide the sun, forcing Kauravas to believe it was sunset and Arjuna’s death was imminent. (In some versions, it is said that Lord Krishna used his yogic power to hide the sun). Overjoyed, they started celebrating, and using that opportunity, Arjuna caught them unprepared, reached near Jayadratha, and made his arrows to carry away Jayadratha’s head. This was because Jayadratha had a boon from his father that whoever would be responsible for his head falling to the ground would have his own head blown up. That is why Arjuna carried the severed head of Jayadratha to his father, who was awoken from his meditation by the sudden landing of a severed head on his body and since he ended up dropping it to the ground, he had his head blown up.