Naval forces were limited to 15,000 men; furthermore, the Treaty specified that the navy could number no more than six battleships of no more than 10,000 tons displacement, six cruisers (6,000 tons displacement), six destroyers (800 tons displacement), and 12 torpedo boats (200 tons displacement), and that these ships could only be replaced after twenty years for the first two classes of ships, and after fifteen years, for the remaining classes of ships. Article 191 specifically prohibited the production or acquisition of submarines. The Treaty further prohibited the manufacture, import and export of weapons and poison gas.[3]