The front cover of the album depicted a British Chieftain tank, which connects to the title, as Salisbury Plain in Wiltshire, England, is a military training area. The original LP release was a gatefold sleeve, with a black-and-white image of the underside of a Chieftain tank on the inside with the turret facing the rear, over which were printed Hensley's comments on each track. Later reissues would be in a single sleeve. The American release on Mercury Records featured a different cover image (a man tearing out of his own skin), as did the original Canadian pressings. Subsequent Canadian pressings used the UK artwork.
Salisbury is skewed toward the progressive rock genre, with its 16-minute title track featuring a 24-piece orchestra. One of the album's tracks, "Lady in Black", described as "a stylishly arranged tune that builds from a folk-styled acoustic tune into a throbbing rocker full of ghostly harmonies and crunching guitar riffs", became a hit in Germany upon its re-release in 1977 (earning the band the Radio Luxemburg Lion award). According to Allmusic, the album perfected Uriah Heep's "blend of heavy metal power and prog rock complexity" and was also significant for Hensley's instant rise to a position as main composer of the group's music. Soon after the release, drummer Keith Baker left the band, to be replaced by Ian Clarke (from another Vertigo band, Cressida). With Clarke, the band embarked on their first US tour, supporting Three Dog Night and Steppenwolf.