//------------------------------//
// The Answer 36 
// Story: Life is a Test: A Series of Pony Logic Puzzles 
// by Brony_of_Brody 
//------------------------------//

With a huge fire blowing their way, the army were forced to fight fire with fire, by starting ANOTHER series of fires, perpendicular to the wind's direction and downwind of the first fire.

This new fire then burned all the vegetation right behind them, and they simply walked on the charred path as it burned through the rest of the island...and towards the kingdom because of the sparks from THAT fire, but...

Anyway, the first fire then had nothing to sustain itself, and it died out.