"A Mistake from the Past: A Face Revealed!" (火影の過ち 仮面の下の素顔, Hokage no Ayamachi Kamen ni Shita no Sugao) is episode 72 of the original Naruto anime.
Sasuke finally manages to catch up to Gaara, but Temari stalls him so that Kankurō and Gaara can escape. He easily deals with her and resumes his chase. At the Hokage battle, Orochimaru reveals his intentions of stealing the body of Sasuke Uchiha. The Third Hokage regrets not killing Orochimaru beforehand. He then shifts his memory to the village that he fights to protect. Making up his mind, the Hokage musters up his chakra and summons shadow clones, in preparation for one final attack.