A means of collectively accelerating an intense electron beam is demonstrated. A long pulse (800 ns) electron beam is propagated through cavity structures which redistributed the energy in the beam such that most of the beam energy is transferred to a short segment (6 ns) in the tail of the beam. Electrons are accelerated in a two cavity system from 200 keV to energies of 2.4–3.0 MeV at a beam current of ∼8 kA. The extension of this principle to larger number of cavities appears feasible.