scorched earth

Short definition from Wiktionary

Noun

1. 1
   Land that has been abandoned, in the face of an advancing enemy, after the destruction of all resources on it.
2. 2
   The strategy of destroying all resources in an area of land in order to deny their use to an advancing enemy.

Adjective

1. 1
   Alternative spelling of scorched-earth.
2. 2
   Characterized by a desire to prevail at any cost.