This expression means to respond to an attack by using a similar method as one's attacker. It is used when somebody applies more extreme methods than he would normally do. The saying comes from the fire-fighting that was taken on by American settlers in the nineteenth century. They attempted to guard against grass or forest fires by deliberately raising small controllable fires, a literal 'fighting fire with fire'. The earliest usage in print was recorded in 1852.

Übersetzung:

den Feind mit seinen eigenen Waffen schlagen

Gegenteil(e)

The opposite of "to fight fire with fire" is "to follow a different tack".

Synonym(e):

You could also say: to pay like with like.