| skos:altLabel | - designs
- Submarines
- submarine
- submarines
- U-18
- German submarine
- German counterparts
- Submarine
- U-Boat
- U-51
- German submarines
- torpedo attacks
- U-Boot
- U-boot
- German U-boats
- torpedoed
- U-boats
- ''Unterseeboot''
- Enemy submarines
- German U-Boats
- German U-boat
- German U-boats in World War I
- German submarine raiders
- German submarine warfare
- Lists of U
- Nazi German submarine
- Type VII U-boat
- U Boat
- U-Boats
- U-Boot-Waffe
- U-boats' torpedo attacks
- U-boats.
- Unterseeboot
- and elsewhere
- covertly develop her U-boat fleet
- submarine menace
- u-boat
- with submarines
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