In the film "Spartacus," the character Crassus remarks that he "fought fire with oil" in regards to him buying the Senate behind his rival's back to appoint his friend to a position of prominence.
The exact exchange:
Marcus Publius Glabrus: "How were you able to get my appointment without Gracchus knowing?"
Marcus Licinius Crassus:
"I fought fire with oil. I purchased the Senate behind his back."
Is this expression akin to "fight fire with fire"? I.e., doing the opposite of what you'd expect by using similar methods? Power with power, as the case may be? I can't find the meaning of it after doing a pretty thorough Google search. If I had to guess, I'd say it means the same as the more common expression, but I'm unsure. Maybe it's a more subtle way of saying you use similar tactics but slightly different methods to achieve an outcome that your adversary would also achieve in his own way?