In December 1917 Germany opens the final, bitter round of the war with a new and deadly weapon in the struggle for the seas. The Vulcan appears to be a harmless merchant vessel. However, her peaceful lines conceal a merciless firepower. She is a commerce raider, and under crack commander Felix von Steiger her mission is to bring chaos to the seaways.
(Not formally known as a series but Captain Von Steiger's son Rudolf commands a U-boat flotilla in With Blood and Iron)