Returning from a U-Boat scouting party. Unidentified aerial naval observer coming down from a blimp after a scouting tour somewhere on the Atlantic Coast. The U-boat Campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Entente Powers. It took place largely in the seas around the British Isles and in the Mediterranean. SS class blimps were simple, cheap and easily assembled small non-rigid airships that were developed as a matter of some urgency to counter the German U-boat threat. Although the SS class types proved invaluable, their use was restricted to coastal patrols in reasonably fair weather owing to their low engine power and comparatively small size. Photo taken by Central News Photo Service, circa 1918.