Contrary to what the other definitions state, the term 'Wall of death' originated in the hardcore punk
community of the early 80s. It was a natural outgrowth of the mosh pit, when people wanted to break into the pit they would form a line and literally rush the pit, becoming part of it.
It became extremely popular, as did slam dancing
and other forms of punk dancing, in the mainstream a few years after it started. This is true for most things punk and true metal did.
One of the clearest examples of this was performed by a crust punk
band with a cult following for the late 90s and early 2000s called R.A.M.B.O. where they would encourage the crowd to dress up as either protestors or cops and stage a mock riot. The two sides would form up and then 'wall o death!' each other.
So, sorry children, Lamb of God did not originate this.