There are 2 bands of this name:

1 - Formed in 1970 around ex-Deep Purple bassist Nick Simper, Warhorse were understandably close to early Deep Purple in their blend of keyboard-colored progressive rock and early heavy metal. The group coalesced when Simper left Deep Purple in 1969 to lead soul singer Marsha Hunt's backing band, which included Rick Wakeman on keyboards for a while. The backing band formed the nucleus of Warhorse, which recorded a couple of albums for Vertigo in the early 1970s. With their early hard rock/metal sounds and a singer (Ashley Holt) who could roll into over-serious, high stentorian vocal phrases, the group have also been compared to early Black Sabbath, although they lacked the hooks necessary to achieve the same level of success as Sabbath or Purple. Echoes of Yes (in the keyboards) and perhaps Uriah Heep can be heard as well. Warhorse broke up in 1973, with drummer Mac Poole joining Gong, and Holt and drummer Barney James (who briefly replaced Poole in Warhorse's final days) going to Rick Wakeman's band.

2 - Finally a band comes along that truly slays! Death Metal played on qualudes! Destructive, brutal black death-DOOM sufficiently sums up the massive Warhorse sound. We're talking riffs soooo heavy, bass soooo low, drums sooo massive, you get the feeling of being beaten slowly with a wet mattress.

However, WarHorse is most definitely not a one trick pony (pun intended). They have contrasted this mammoth heaviness with a unique use of dynamics.

One minute you're drawn into a trance; like a state with soft, dark, quiet passages. The next violently struck by enormously bombastic dirge riffs.

This extreme use of dynamics (read: loud/quiet) and dark atmosphere even brings to mind the work of Slint, or Pink Floyd. Call them the Slint of Sabbath!

This technique is what sets apart WarHorse from the thousands of pretenders to the throne.