I looked it up in the old manual
Victory Level Your VP minus Enemy VP
Decisive Victory 51 to 100
Marginal Victory 16 to 50
Draw -15 to 15
Marginal Defeat -16 to -50
Decisive Defeat -51 to -100
So 3 points away from a decisive victory.
I was 2 points away from my maximum, so one would have to look at the German objectives to see where I should have improved.
I guess I should have taken less casualties, because I can't see how to advance much faster.
Anyway, I think it was a decent fight. Crossing the bridge and consolidating in the first open polder area is bloody business anyway, but it happened during the night and that helped.