That's Old Man's War (2005, Scalzi) [0], itself a twist on the (much darker) The Forever War (1974, Haldeman) [1]. Both are predicated on the extra-Earth facti

That's Old Man's War (2005, Scalzi) [0], itself a twist on the (much darker) The Forever War (1974, Haldeman) [1]. Both are predicated on the extra-Earth faction having overwhelming technological superiority and resources. Gravity is not that helpful. So, not "initial colony" stages. [0] https://en.m.wikipedia.org/wiki/Old_Man%27s_War https://en.m.wikipedia.org/wiki/Old_Man%27s_War [1] https://en.m.wikipedia.org/wiki/The_Forever_War https://en.m.wikipedia.org/wiki/The_Forever_War