[3] The Irish state has a long-standing policy of non-belligerence in armed conflicts, including neutrality in World War II.

The IRA divided between those who accepted the decision of the Dáil in ratifying the Treaty and those who did not: consequently, both civil war and re-occupation by the British became possible.

[16] With declining relations between the remaining units of the anti-treaty IRA and the newly recruited pro-treaty National Army, the Irish Civil War broke out on 28 June 1922.

It ended in victory for the National Army when, on 24 May 1923, the anti-treaty IRA Chief of Staff, Frank Aiken ordered his volunteers to dump arms.

As the Emergency progressed, more and newer equipment was purchased for the rapidly expanding force from Britain and the United States as well as some manufactured at home.

[18] G2, the Army's intelligence section, played a vital role in the detection and arrest of German spies, such as Hermann Görtz.

The first contribution to peacekeeping was in 1958 when Army officers were assigned to the United Nations Observation Group in Lebanon (UNOGIL).

Since 1958 the Defence Forces have had a continuous presence on armed United Nations peacekeeping operations, except between May 1974 to May 1978 (although they did retain overseas unarmed observer missions during this period).

[19] During the Troubles, the period of civil conflict centred on Northern Ireland from 1969 to 1998, the Defence Forces deployed to aid the Garda Síochána.

[citation needed] In 1969-70, there were proposals considered for a limited military intervention in Northern Ireland to protect the nationalist commmunity, known as Exercise Armageddon, but it was seen to be unworkable and was not adopted by the cabinet.

[20] Although units were moved to the border region in 1969–70 during the Battle of the Bogside, in order to provide medical support to those wounded in the fighting.

[citation needed] In 1978, cash-in-transit escorts were established to protect large cash movements throughout the state, continuing until 2014.

[22] The Central Bank of Ireland had the Government put in place contingency plans to provide armed Defence Force security for major Irish banks over public order fears if a cash shortage was triggered at the height of the 2008/2009 financial crisis.

As part of the plans to move to "Level of Action 2", as of 2022, the number of civil and military personnel was set to be increased from 9,500 to 11,500.

[26] The Defence Forces specified the procurement of an integrated radar system for land, sea and air function and that the Army's structures and capabilities would be redesigned to meet "international best practice".

In addition to the brigade structure, there is also the Defence Forces Training Centre, a logistics base in the Curragh.

Most weapons used by their defence forces follow NATO standards and are purchased from abroad, with Ireland having a very limited arms industry.

The Air Corps has six AgustaWestland AW139 utility helicopters capable of being armed with FN MAG machine guns.

These are used in support of the ARW, Naval Service and Garda Síochána operations, and are the only helicopters within the state capable of flying at night in mountain terrain using night-vision technology.

The eight Pilatus PC-9 turboprop trainers can be equipped with rocket pods and machine guns, and two Eurocopter EC135 light utility helicopters (which can be used as sniper platforms by the ARW) are used for training pilots and for air-ambulance missions.

[35] The Naval Service maintains a complement of approximately 725 active personnel[12] and 97 reserve personnel[3] and is tasked with patrolling Irish territorial waters as well as the Irish Conservation Box, a large area of sea in which fishing is restricted to preserve fish numbers.