Related Clues:

• Battle of the Atlantic attackers
• ''Das Boot,'' for one
• Liner threat, once
• Depth charge target
• World War II sub
• "The Enemy Below" threat
• Convoy chaser
• WWII submarine
• Sub with sauerkraut?
• Depth charge targets
• W.W. II blockade enforcer
• Destroyer hunter
• Submerged threats of WWII
• Torpedo launcher
• WW II sub