It belonged to the U-boat under the command of Lieutenant Otto Hersing.

Entity and relation annotations:
id: 0
type: entity
value: text: Lieutenant
labels: <Title>
id: 1
type: entity
value: text: U-boat
labels: <Production>
id: 2
type: entity
value: text: Otto Hersing
labels: <Person>
type: relation
to_id: 0
labels: Person:holds_title:Title
from_id: 2
type: relation
to_id: 1
labels: Person:owns/uses:Production
from_id: 2