how significant is national morale in land combat

[scout1]

Just how much of an impact does the difference in national morale between attacker/defender have on combat results ?
Everything else being ~equal...

The battles by 1916 become more and more one sided when I'm playing the CP against me

[Peek101]

According to the manual, NM has the following effects on unit morale:

If National Morale < 40% then Unit Morale is multiplied by 0.85.
If National Morale < 75% then Unit Morale is multiplied by 0.90.
If National Morale < 95% then Unit Morale is multiplied by 0.95.
If National Morale > 110% then Unit Morale is multiplied by 1.10.