Depends on a lot of factors like:
How far do you have to go? A very light pack, flat ground, good conditions and only a couple of miles to go, somewhere at the other end where I can kick back and relax for a few hours and I might have jogged it at a good six, maybe seven miles per hour. Older now, I might manage five miles an hour if you sic the dogs on me.

Heavy pack, up and down mountains, lousy weather, little opportunity to rest, limits on food and water, and the realization I have to do it every day for a month may limit my pace to about one mile per hour. Maybe a bit faster. Particularly on the down slopes.

I usually figure about two miles per hour and estimate I lose about a third of that pace if I'm going up and down mountains or slogging through swamps.

Extreme conditions can cause you to have to go slow and cover several times the distance on the ground that you cover on the map. Historically going through dense jungle and near vertical slopes trained troops sometimes only cover a mile, perhaps two miles, on the map in a day.

Forced by events highly capable and motivated people have often completed remarkable feats of strength, toughness and endurance. Sometimes coming across the line half-dead after giving everything they have to give. At the same time others have died in the attempt. History is full of these death marches.