From the Steven Stills website

By 1972, what we call classic rock was pretty much peaking – though nobody at the time knew it. Except maybe Stephen Stills. The band and double-album he piloted and released that year—both named Manassas—now seem pivotal. Manassas brilliantly summed up the remarkable 1960s creative surge that revitalized rock’s roots and encouraged experimentation just when it was at its crest.