At WrestleMania XV, Triple H lost to Kane after Chyna interfered on his behalf and she was thought to have rejoined D-X. Later on in the night, he betrayed his long-time friend and fellow D-X member X-Pac by helping Shane McMahon retain the European Championship and joined The Corporation. turning heel in the process. In April, he started to move away from his D-X look, taping his fists for matches, sporting new and shorter wrestling trunks and adopting a shorter hairstyle. His gimmick changed as he fought to earn a WWF Championship opportunity. After failed attempts at winning the championship, Triple H and Mankind challenged then WWF Champion Stone Cold Steve Austin to a triple threat match at SummerSlam, which featured Jesse "The Body" Ventura as the special guest referee. Mankind won the match by pinning Austin. The following night on "Raw Is War", Triple H defeated Mankind to win his first WWF Championship. He dropped the WWF Championship to Mr. McMahon on the September 16, 1999 episode of "SmackDown!" before regaining it at Unforgiven in a Six-Pack Challenge that included Davey Boy Smith, Big Show, Kane, The Rock and Mankind. He defeated Stone Cold Steve Austin at No Mercy before dropping the title to Big Show at Survivor Series. Triple H then continued his feud with Mr. McMahon by marrying his daughter Stephanie McMahon and defeating McMahon at Armageddon. As a result of the feud, an angle with Triple H and Stephanie began which carried the WWF throughout the next seventeen months; together they were known as The McMahon-Helmsley Faction.