 Later evolutions launched variants of self-propelled Whitehead torpedoes.These were inshore craft created to counter both the threat of battleships and other slow and heavily armed ships by using speed, agility, and powerful torpedoes, and the overwhelming expense of building a like number of capital ships to counter an enemy's.A swarm of expendable torpedo boats attacking en masse could overwhelm a larger ship's ability to fight them off using its large but cumbersome guns.