The Naval Service is the maritime component of the Defence Forces of Ireland and is one of the three branches of the Irish Defence Forces. Its base is in Haulbowline, County Cork.

Though preceded by earlier maritime defence organisations, the Naval Service was formed in 1946. Since the 1970s a major role of the Naval Service has been the provision of fisheries protection in Ireland's exclusive economic zone (EEZ). Other roles include sea patrol, surveillance, and smuggling prevention. Occasionally the Service undertakes longer missions in support of other elements of the Defence Forces, Irish peacekeepers serving with the United Nations, or humanitarian and trade missions.

LÉ Eithne is the current flagship of the Naval Service.

The Anglo-Irish Treaty of 1921 stipulated that the Irish Free State would be given responsibility to police its customs and fishing, while the United Kingdom would remain in control of Irish waters. In 1923 the Coastal and Marine Service (CMS) was created, yet about one year later it was disbanded.

During the Civil War, in August 1922, a ship belonging to the British & Irish Steam Packet Company, Lady Wicklow, led by Captain Patrick Ryan, was used to bring Irish National Army troops around the coast to Fenit, the port of Tralee in County Kerry. This naval involvement technically preceded the foundation of the Irish state, as Ireland was still part of the UK at the time. Built in 1890 in Dublin Dockyard, the ship measured 262 by 34 feet (80 by 10 m). In all 450 troops, including officers, were landed. Tralee was later captured from local republican forces.

Muirchú, formerly the British armed steam yacht Helga, which had been used by the Royal Navy to shell Dublin during the 1916 rising, was the only CMS ship during this period. The CMS ship Muirchu continued to patrol Irish fisheries. Muirchu was re-armed in 1936 and purchased by the Irish government on advice of members of the later named Maritime Institute of Ireland for fisheries protection.

In 1938 the United Kingdom handed over three "treaty" ports (Cork Harbour, Bere Haven and Lough Swilly). Consequently, the Royal Navy withdrew from Cork Harbour in July 1938. Fort Rannoch was added to the Irish fleet at that time.

In 1939 the Irish Government ordered two Motor Torpedo Boats (MTBs) from Vospers UK. When World War II began in September 1939 the Marine and Coastwatching Service was set up. In order for Ireland to remain neutral, it became clear that a full naval service would be required. The government consequentially ordered an additional 4 MTBs. By the end of 1940 the Irish Marine and Coastwatching Service consisted of 6 MTB's and 4 other assorted craft.

During the War the Service protected fisheries, regulated merchant ships, and laid mines off Cork and Waterford. By 1941 the Marine and Coastwatching Service consisted of 10 craft (6 MTBs plus 4 assorted vessels) and about 300 all ranks. In 1942 the Service was renamed the Marine Service.

In September 1946, the Marine Service was formally disbanded and the Naval Service established as a permanent component of the Irish Defence Forces. The Naval Service purchased three Flower-class corvettes from the United Kingdom in 1946 and 1947. The tradition of naming Irish Naval Ships after figures in Celtic Mythology began, and the ships were named Cliona, Maev and Macha. These three ships were to become a key part of the Naval Service in the 1950s and 1960s. The first formal training of Irish naval cadets took place at the Britannia Royal Naval College, Dartmouth, UK in 1947. In 1970, Cliona and Macha were withdrawn from service and scrapped, leaving Maev as the sole ship in the Naval Service. Maev was withdrawn from service in 1972. In 1971, the Naval Service commissioned three armed Ton-class minesweepers: Grainne, Banba and Fola.

In 1971 the Naval Service commissioned Verolme Cork Dockyard to build an offshore patrol ship. Named LÉ Deirdre, it was the first naval vessel purpose-built in Ireland to patrol its waters. The Economic Exclusion Zone of Ireland was increased in 1976 from 12 miles (19 km) to 200 miles (320 km)s. The subsequent strain put on the Naval Service prompted funding from the European Economic Community to acquire five additional vessels, four of which were eventually built. Meanwhile, the former Irish Lights vessel Isolda was purchased to act as a training ship, bearing the pennant number A15 and renamed LÉ Setanta. It served until being sold for scrap in 1984. A Danish stern trawler Helen Basse was also leased for a year, serving under the name LÉ Ferdia, pennant number A16.

The 50th anniversary of the Naval Service took place in 1996. Celebrations included a fleet review by President Mary Robinson. In 1999, a new ship LÉ Róisin was delivered to the Naval Service, marking the beginning of a new class of larger patrol vessels followed by LÉ Niamh, commissioned in September 2001 replacing LÉ Deirdre.

While most missions undertaken by the Naval Service are in Irish waters, on occasion longer missions are undertaken in support of Irish Peacekeepers serving with the United Nations, representing Ireland, or in support of Irish trade missions. In 2002, LÉ Niamh delivered supplies to Irish troops in Eritrea, then continued on a trade promotional tour to India, Malaysia, Singapore, Hong Kong, China, Korea, and Japan, becoming the first Irish naval vessel to cross the Equator. In 2006 LÉ Eithne travelled to Argentina, attending ceremonies connected with the 149th anniversary of the death of Irish-born Admiral William Brown, founder of the Argentine Navy, and also visited ports in Uruguay and Brazil. In 2010, Niamh travelled to the Americas, visiting Brazil, Argentina, Chile, Mexico and the United States.

In 2010, two new ships were planned for the Naval Service. The first, LÉ Samuel Beckett, was delivered in April 2014 replacing LÉ Emer, and the second, LÉ James Joyce, replaced LÉ Aoife in 2015. The option for a third, LÉ William Butler Yeats, was exercised in June 2014 and is due for commissioning before the end of 2016. The new ships displace over 1,900 tons, have a top speed of 23 knots, a range of 6,000 nautical miles. They are armed with an OTO Melara 76 mm/62, and have a longer deck area that can accommodate deep-sea search-and-rescue submarines and unmanned aircraft.

In May 2015, it was announced that the Naval Service would deploy a ship to the Mediterranean to form part of the EU humanitarian response to the European migrant crisis.The fleet flagship, Eithne, left Cork on 16 May 2015, led by Commander Pearse O'Donnell, for an eight-week deployment to the region, during which time the ship picked up a total of 3,377 people in the waters between Libya and Sicily. In July, the mission was extended with the deployment of first, Niamh from July to September, and then Samuel Beckett from September until November.
You will find links to buy products from Amazon, Google and other partners. If you click on these links, you’ll find that the URL includes a small extra piece of text which identifies that the click came from my websites. This text is an affiliate code, and it means that I get a small percentage of the money you spend if you choose to buy that product, or, in some cases, other products from the site soon after. These affiliate links help pay the costs of producing my websites and ensure that the content is free to you.