A series of conflicts between Great Britain and Iceland over how far the Icelandic territorial waters should extend. The first Cod War occurred in 1958 when Iceland's fishing limits were moved from 4 miles to 12 miles away from the coast. The British tried to stop the change by sending frigates to the area but were unsuccessful, and finally the dispute was settled by an agreement confirming the change. The second Cod War began in 1972 when the limits were extended to 50 miles off the coast. Again, the British protested and appealed to the International Court of Justice in The Hague which found the expansion to be unlawful. Iceland ignored the ruling, and eventually expanded the limits even further, to 200 miles, in 1975 without having resolved the old dispute. This was the start of the third Cod War, which lasted from November 1975 to June 1976, and is probably most worthy of the three of being called a war. Great Britain didn't accept the change and continued to fish inside 200 miles, which prompted Iceland to send 8 Coast Guard ships to enforce the new limit. In response Great Britain sent numerous frigates, supply ships, and tug boats to protect the 40 trawlers in the area. In the end, after Iceland had cut diplomatic relations with Great Britain and threatened to close down the NATO base in Keflavik, the conflict was resolved through the mediation of NATO. Great Britain was given a six month adaption period in which they were allowed to catch 50,000 tons, but after that they had no right to fish within the 200 mile limit.
Iceland's main argument for constantly extending their fishing limits was that without protection the fish stock (cod in particular) would grow smaller and smaller and eventually disappear from the area. This was particularly important since at the time fish accounted for around 90% of Iceland's total export revenue and was crucial for the country's survival. This over-exploitation was, according the Icelandic government, caused by foreign ships catching too much, and so they wanted to completely block them from the area. Over-exploitation had already caused the collapse of the Icelandic herring stock in the 1960's in spite of Iceland's numerous warnings to the international community. To prevent the same from happening to the cod they felt that unilateral expansion was neccessary.
Few shots were fired during the Cod Wars. Instead, Icelandic Coast Guard Ships cut the nets of British trawlers and many rammings occurred between ships. To cut the fishing nets the Coast Guard used cutters that were specifically designed for that, and that technology has since been used by many nations who have needed to protect their waters from fishing.
The result of the Cod Wars was very important to Icelanders. Not only had they succeeded in protecting their most important resource, they had also stood up to one of the world's most powerful countries and won.
Sources:
Various books,
http://home.freeuk.com/nigelhadley/codwar.htm