In situations where a smaller weaker force is faced with a stronger larger force, Sun Tzu's tactics are very often successful. David and Goliath is a Biblical story of a weaker shepherd boy facing a giant who is a skilled warrior. David uses an unconventional weapon and slays Goliath. David refused to fight by Goliath's rules. Political scientist Ivan Arreguín-Toft did calculations on wars. He discovered that about a third of the time the weaker country actually wins.