Thousands of British naval mines like this were laid underwater to counter German surface ships and submarines.

Small wheels on the base allowed the mine to be rolled off the stern of ships laying minefields. Britain's Royal Navy used thousands of mines to create barriers intended to damage or sink German surface ships and submarines, or to deter them from entering areas where minefields were known to exist. In the English Channel, mines formed part of extensive anti-submarine barriers that also used nets and were supported by motor launches and larger vessels.

Naval Mine, British Type "H", Mk IV
CWM 19390002-837