Haldeman doesn't use Ramjets in 'Forever War'[0], since the soldiers have access to Collapsars (black holes?) for instantaneous point-to-point jumps. He doesn't

Haldeman doesn't use Ramjets in 'Forever War'[0], since the soldiers have access to Collapsars (black holes?) for instantaneous point-to-point jumps. He doesn't describe the drive technology that gets them from between planets and the collapsars, except to say that the ships were 'converted cattlewagons ... with extra reaction mass' [0] https://en.wikipedia.org/wiki/The_Forever_War https://en.wikipedia.org/wiki/The_Forever_War