In TAO, combat and movement are integrated. You can partly move one regiment, fully move another regiment, fight a battle, then continue the first regiment's movement where you left off. There are some restrictions. A unit can only attack once per turn. Fighting a battle causes 'combat residue' slowing units passing through a vacated defender's hex.
Supply is neat too.
Being cut out of supply does not instantly reduce the fighting ability of units. If it breaks the encirclement, good. After that, it has lost its DCC until it is back in supply. A unit without DCC always has to retreat after combat. A CRT mandated retreat becomes an additional loss.