I've had a few times offroad in snowy/icy conditions in my A0 where ANY amount of braking resulted in locking the wheels.
In one instance, I was traveling at idle speed, on an icy trail with a slight side slope (a couple degrees, similar to an on-ramp embankment). When I hit the brakes even the smallest amount, it locked the wheels and began a slow sideways slide off the trail. This left my only option to not brake at all, and keep going at idle speed. The problem was that there was another vehicle in front of me that I kept getting closer and closer to, until I was within inches.
I'm not sure if ABS would have helped it, but without it the results were not good.