“Mercy” is a song that has only been released as a track from concert, appearing on 2010’s Wide Awake in Europe EP.
The song “Mercy” was first mentioned in a fall 2004 Blender magazine article, where Blender sat in on a session where U2 tried to settle the final running order of “How to Dismantle an Atomic Bomb”:
As it stands, the album is three seconds shy of an hour and, as Bono says, “too much of a good thing is a bad thing,” so drastic measures need to be taken. “I have a theory,” Mullen begins, and a reverential silence descends as the drummer — traditionally the first band member to be shouted down in these situations — states his case. After just five minutes, it has been unanimously decided that the track “Mercy,” a six-and-a-half-minute outpouring of U2 at its most uninhibitedly U2-ish, must go. Hence a song that any self-respecting band would be proud to call a single becomes what Bono immediately anoints “the best B-side you’ve ever heard.” Later, another more experimental candidate entitled “Fast Cars” (“an Irish/Mexican vibe”) gets evicted, and the album becomes a lean and lithe 11 tracks.
The song didn’t disappear however, in November of that year, just after the album was released, “Mercy” appeared on the internet as a low quality digital file. The song was initially posted on the Interference message boards, by a fan who claimed to have gotten the song from a friend. That friend, would later tell the message board that he had received a copy of the album about a week and a half before the album was released, and it was given to him on cassette by a friend at Interscope Records. The cassette was digitized and burned to CD, and it was played for a group of fans at a house party, and was later ripped from that CD and uploaded to Interference the week of the album release. The claim was made that the song on the cassette sounded unmastered and that some of the levels seemed ‘funky’ even in that format.
In May 2007 Bono told an Italian fan, who posted the information on U2Place.Com, that “Mercy” would be included on the next album, and that Bono had no idea how the song had reached fans on the web. In 2009 during a promo radio appearance at XRT Radio in Chicago, The Edge told fans that the band really like “Mercy” but just haven’t figured out where to use it. The band had toyed with using it for the album No Line on the Horizon, but in the end it was held back for Songs of Ascent.
During the 2010 leg of the U2360 tour, U2 introduced a number of new songs to the set throughout the leg. “Glastonbury,” “North Star,” and “Return of the Stingray Guitar” were all introduced for the first time on August 6, at the opening show of the tour in Turin, Italy. (“Glastonbury” had been sound checked August 1, 2, 3, 4, and 5 (five times!), “North Star” had been sound checked on August 2, 5 (twice), and “The Return of the Stingray Guitar” was sound checked on August 4 and 5.) Another song debuting was “Every Breaking Wave” on August 21, 2010 at Olympic Stadium in Helsinki, Finland. “Mercy” made it’s tour debut on September 12, 2010 in Zurich, Switzerland at Letzigrund Stadion. And on October 3, 2010, U2 debuted “Boy Falls From the Sky” at Estadio Cidade de Coimbra in Coimbra, Portugal. “Mercy” was played at 10 shows, making its debut on September 12 in Zurich, and last being played on December 9 in Brisbane, Australia.
A studio version of “Mercy” remains unreleased at this point.