Port. A French sailor hangs on the wall a manifesto declaring war with Germany, other sailors run up and read the manifesto. A detachment of cruisers at sea. Sailors are preparing mine vehicles for battle. The sailors run up to the guns, shoot. Loading mines onto a ship using a crane. A sailor loads a torpedo into the bow of a submarine. The sailors raise the gun from the shelter on board the submarine, point it, put it back. Submarine dive. The commander looks through the periscope. Periscope on the surface of the water. The mechanic is at the instruments. The sailors are loading the gun. A torpedo is floating. Explosion at sea. A submarine emerges. The guns are firing at the stern of the ship. Ships and submarine at sea.