When Julius Cesar was little more than a rebel against the Roman Republic, he faced near certain ruin against Pompey's great international armies.
The night before the final battle, outnumbered more than 2 to 1, Cesar ordered his army: "Pull down your own ramparts and fill in the ditch, so that if we fail to win we shall have nothing. And the enemy shall see that we lack a camp, and that necessity compels us to make our quarters in theirs."
The took the battle with no hope of retreat. The only two options were win or die.