1976's The Book of Invasions was Horslips sixth studio album (it was their seventh album, if you include Horslips Live which was released earlier in 1976) and is regarded by many as one of their better albums. It's also a concept album dealing with The Book of Invasions (called Leabhar Gabhála Éireann in Gaelic) which chronicles the various colonies of pre-Christian Ireland, and about the various pagan beliefs of the inhabitants and much more. The band at that time featured Charles O'Connor on fiddle, mandolin, concertina, and vocals, Jim Lockhart on keyboards, flute, and whistles, Barry Devlin on bass and vocals, Johnny Fean on guitar and vocalist, and last, but not least, Eamon Carr on drums.

At times, their music will bring to mind Jethro Tull, thanks to Lockhart's flute playing, which is not unlike Ian Anderson, but thanks to the Irish bent to their music, you know you can't mistake them as Tull-soundalikes (and besides, none of the vocalists sound anything like Anderson). The album is divided in to three movements ("Geantraí", "Goltraí", and "Suantraí") divided in to many suites that basically sound like separate songs.

The album starts off with "Daybreak" which is a rock adaptation of a drinking song, "Tá 'na lá", but it's all instrumental. It then segues in to the ever wonderful and Tull-like "Trouble with a Capital T", which is a favorite amongst Horslips fans, and for good reason, it's definately one of the highlights on this album. Lockhart's flute playing here reminds me a bit of Thick as a Brick.

The next song is another rocker, "The Power and the Glory". But because the flute isn't present, it doesn't sound much like Tull. "The Rocks Remain" is a softer number with vocals harmonies that oddly remind me of the Byrds. This is one song that really grew on me big time.

After that song, the theme to "Daybreak" is repeated, but keeps getting interrupted by a jig played on fiddle. It then segues in to "Sword of Light", another highlight of this album. Here, a jig called "Toss the Feathers" is incorporated in to this song, and if this jig sounds a little familiar, it should: "Toss the Feathers" was one of the jigs included on Fairport Convention's Liege & Lief. Regardless, "Sword of Light" is just amazing. The second movement ("Goltraí") opens up with "The Warm Sweet Breath of Love", which, like "The Rocks Remain", is one of the softer numbers on the album. For some odd reason, the vocals here remind me of Gerry Rafferty.

The next song is an instrumental called "Fantasia (My Lagan Love)", which is another adaptation of a folk song. It does tend to be rather moody (a theme of this song started off "The Warm Sweet Breath of Love", except it was played on concertina, rather than guitar). The next song is another highlight of the album, "King of Morning, Queen of Day" which incorporates a Claire jig called "Kilfenora". The song starts off with electric piano, which I find a little odd and out of place for the kind of music that Horslips plays (the electric piano is much more common in straight-up prog rock bands and fusion bands à la Weather Report).

The album then closes with the final movement ("Suantraí"). It doesn't start off all that great, because I thought "Sideways to the Sun" was rather mediocre, and even after repeated listens, it fails to excite me, but luckily the album closes off with a bang with the ever wonderful "Ride to Hell", which is up there with "Trouble with a Capital T" and "Sword of Light" as the best song on the album. Anyway, this is another great album from this Irish band (following Horslips albums like 1977's Aliens and 1978's The Man Who Built America are more rock oriented with less of that Celtic influence). If you fancy the idea of Celtic rock, then get The Book of Invasions.