It is usually relevant to a condition or state of war where one side depletes the resources of another through attrition.
For example, the German objective at the Battle of Verdun (1916) during World War I was not the seizure of any strategic objective, but rather to inflict an LER of 2:1 on the French forces and thereby cripple the French army.
[dubious – discuss] During the First Indochina War, Võ Nguyên Giáp, the leader of the Việt Minh, told his French opposite number that "you can kill ten of my men for every one I kill of yours, and at that rate, I will still triumph."
In fact, the LER was approximately 3:1 in favor of the French, and they did indeed withdraw in defeat.
A total of 500,000+ Vietnamese were either killed, wounded or captured during the First Indochina War.