In the Wake of Poseidon (1970) is the second album by the progressive rock group King Crimson. By the time this album was released, the band had already undergone their first change in lineup, however they still maintained much of the style of their first album, In the Court of the Crimson King.

Also like their first album, the mood of this album often changes from serene to chaotic. The album opens with a poetic vocal piece called "Peace-A Beginning", which is reprised instrumentally in the middle of the album and vocally again at the end. The longest track on the album is a chaotic instrumental piece called "The Devil’s Triangle", basically a renamed version of 19th Century composer Gustav Holst's "Mars: Bringer of War" from his The Planets Suite. King Crimson would have called the piece Mars, as they had performed it on tour in the 1969 lineup, but were forbidden by the composer's legal estate. In 1971 a brief excerpt from "The Devil’s Triangle" was featured on the BBC television series Doctor Who.

Track listing

1. Peace - A Beginning (Fripp/Sinfield) 0:49
2. Pictures of a City (Fripp/Sinfield) 8:03, including:
   • 42nd at treadmill
3. Cadence and Cascade (Fripp/Sinfield) 4:27
4. In the Wake of Poseidon (Fripp/Sinfield) 7:56, including:
   • Libra’s Theme
5. Peace - A Theme (Fripp) 1:15
6. Cat Food (Fripp/Sinfield/McDonald) 4:54
7. The Devil’s Triangle 11:39, including:
   • Mesday Morn
   • Hand of Sceiron
   • Garden of Worm
8. Peace - An End (Fripp/Sinfield) 1:53

Personnel

• Robert Fripp (guitars, mellotron and devices)
• Greg Lake (vocals)
• Michael Giles (drums)
• Peter Giles (bass)
• Keith Tippett (piano)
• Mel Collins (saxes and flute)
• Gordon Haskell (additional vocals on track 3)
• Peter Sinfield (words)