Ok, after reading again...this is what happened. Driving in loose sand for 15 miles (with horrible street tires, inflated) in 2d caused the ATF to get so hot that is foamed and the gear no longer had the ability to make contact/spin?

I guess that makes sense, but I do wonder why, after stopping for 5 minutes, I was able to put it in drive and move the vehicle about 50 yards, without a problem. Was the 5 minutes long enough for the coolant to cool?

1998 Mitusbishi Montero (winter package)
1987 Land Rover One Ten