The First Punic War - The Corvis

The corvis functioned like a narrow drawbridge. Each roman ship had a wooden column outfitted with a pulley mounted on its prow. Attached to the pulley was a narrow plank with a large metal spike protruding from its bottom. When the romans got near enough to an enemy vessel, they dropped the corvis, which crashed into the enemy deck and held the ship in place. An initial fore of 30 carthaginian ships were all caught up and their crews slaughtered. Having taken the carthaginians completely by surprise with their new toy, rome won its first major naval battle handily. Once the secret weapon no longer secret, its effectiveness disappeared.