Off the top of my head the book Manthropology by Peter McAllister covers some of this, as far as what was expected of the ancient solider.
Also look into the history of Special Forces in the United States. WWI was in large part trench warfare, the Civil War was largely fought in open fields in lines not unlike trench warfare. Marching was something you did for parades and pageantry.
Basically though if you look at ancient armies like the Romans had you needed to be able to march 15-20 miles in full kit over most terrains and this is how you trained.
If you want to dive into the current Special Forces community you need to start with the First Special Service Force where you first start seeing long marches (on a 60 mile course) as well as learning things like hand to hand combat, skiing, mountain climbing, parachuting. Then go look at Darby's Rangers and Merrill's Marauders. From there jump to to Vietnam and the 5th SFG[A] and look at some of their feats.
Today you have stuff like Robin Sage and Operator Training Course which, special tactics aside, some ancient soldiers would felt right at home with the long range marches and covering unimproved terrain as well as handling shelter and meeting their basic needs.
If you really dive into the history of special forces and the backgrounds of the original trainers/leaders, you'll see men with well rounded knowledge of ancient tactics/warfare as well as knowledge/training in more modern, yet primitive, tactics like guerrilla warfare and taking on much larger forces (again, something that there are great examples of in ancient warfare like the Battle of Marathon, Battle of Julu, Battle of Badr) as well as ancient units/groups (Medjay, Akkadian, Spartan, Sacred Band of Thebes, Dacian, Varangian Guard etc).