"at least there were people around to help out."
That's the fundamental right there!
The spring pack, all of the leafs, snapped at the front edge of the axle mount.
Cause...???
Springs too worn out?
Jim a too heavy on the skinny pedal (I do recall giving it "a bit" of gas before the snap)?
Jeep slip and fall atop the ledge rock and catch the front of the spring causing an odd force to the leafs?
It "doesn't take much" abuse to break steel. I was in the driver's seat on this one. I recall Alex snapping a rear drive shaft U-joint on Big Momma. It does not take much... thus the fundamental to always go with help at hand...