Táin Bó Cúailnge
Cuchullain goes to Medb's army alone.  At night, he attacks the sleeping soldiers with his slingshot, killing many.  The next day, he makes a deal with Medb's army: They choose one warrior to fight him in one man against one man.  If they do this, Cuchullain will not attack them at night.  If Cuchullain wins, the army must stay still until the next day.  If the other fighter wins, Cuchullain will die.