Conflict with the United Kingdom led to a collection of so-known as Cod Wars, which incorporated confrontations involving the Icelandic Coast Guard and the Royal Navy in excess of British fishermen: in 1952-1956 because of to the extension of Iceland's fishing zone from 3 to four nmi (5.6 to 7.4 km 3.5 to 4.6 mi), in 1958-1961 following a additional extension to twelve nmi (22.2 km 13.8 mi), in 1972-1973 with a further extension to fifty nmi (92.