One thing I find fascinating about some soldiers of the Civil War is that infantry troops often marched 20-30 miles a day and then went into battle. Stonewall Jackson's foot cavalry were known for marching 30 miles a day to outflank some union troops. I don't think troops of today could match this activity. I remember marching to the rifle range at Ft. Benning in 1969 in July and after 90 minutes of marching in the heat the troops began to fall out left and right. We were not carrying packs, but just our rifles and canteen of water. As soon as the water ran out troops began to collapse. I think our ancestors were made of tougher stuff.