There are two bands called Henceforth. HencefortH (note the last H) is a melodic oldschool hardcore band from Amsterdam, the Netherlands. www.caretodancewithus.com Their last album is called "An Ambush Among Friends" A couple of songs you can find on Last.fm. There's also a Youtube clip on here!
Henceforth is a heavy metal, progressive rock band from Brasil and first saw the light of day back in 1993, when Hugo, Fabio (both former members of Wardeath, a trash metal band) and Andre Nikakis (former Final Garden bass player) got together to start a new band.