haven’t read all the post but steep and muddy. I would’ve had it in low and maybe feather brake. Maybe and try and steer out.
I just stay away from steep inclines when it’s muddy like that. For real. I’ve had my share of similar sliding backwards. Glad all is well.
Just catching this thread. To answer the original question, not knowing about the broken brake line, which doomed them from the beginning, engine braking and 4-Lo is a must. It’s the only way I go down steep and/or sketchy terrain. I feel bad for them.