This device, though at the time not so named, was a key
factor in English victory over the French at Agincourt.
The French made a very unwise choice of terrain. They chose one end of a sort of figure of eight shaped plain, with
a constriction caused by waist high bushes separating them from the English. The English King Henry V had archers cut
long staves, sharpen the ends, and drive them into ground
with one end pointing towards the French, so that when the French cavalry tried to attack the English archers, the hidden spears disabled their horses, and the English archers
were able to kill hundreds of the French.
I resisted temptation to say the spears made the French cavalry "hors de combat".