On 20 March 1919, a group of 30 Irish Volunteers, including five employed by the RAF, stole 75 rifles and 5,000 rounds of ammunition from the base.

[9] In 1936, the Executive Council of the Irish Free State established a new civil airline — Aer Lingus — which began operating from Casement Aerodrome, at Baldonnel.

By the end of 1939, a grass airfield surface, internal roads, car parks and electrical power and lighting were set up.

[10] FitzGerald, who had designed an airport terminal as part of his college studies, led a team of architects that also included Kevin Barry, Daithí Hanley, Charles Aliaga Kelly, Dermot O'Toole and Harry Robson.

The terminal building opened in early 1941, with its design heavily influenced by the tiered structure of the luxury ocean liners of the time.

The terminal was awarded the Triennial Gold Medal of the Royal Hibernian Institute of Architects in 1942 and is today a listed building.

[citation needed] Due to World War II, which was known as The Emergency in Ireland, services were severely restricted at Dublin Airport until late 1945.

The only international scheduled routes operated during this time were by Aer Lingus to Liverpool (and for a period to Manchester's Barton Aerodrome).

[12] In his 1969 book Irish Pubs of Character, Roy Bulson describes the restaurant in Dublin airport as "one of the best airport restaurants in Europe" which served a table d'hôte lunch from noon until 3 pm, and hosted regular Saturday night dinner dances from October until April which had become very popular by that point.

[17] In 1983 Aer Lingus opened its 'Aer Lingus Commuter' division[18] which took delivery of Shorts, Saab AB and Fokker turboprop aircraft to open regular daily domestic services to and from Ireland's smaller regional airports for the first time, as well as to serve existing routes to smaller regional airports in the United Kingdom.

Most of these routes have since been discontinued as the development of the motorway network in Ireland has resulted in significant reductions in travelling time by road.

The ground floor of the original terminal building was returned to passenger service after many years to provide additional departure gates.

Pier D, completed in October 2007, is a dedicated low-fares boarding area and provides 14 quick turn-around stands and departure gates; these are not served by air bridges.

[22] The demand from Ireland's migrant workers, principally those from Eastern Europe, has resulted in a large number of new routes opening to destinations in the European Union accession states.

[25] In August 2019, Dublin Airport was chosen for the Special Achievement in Geographic Information Systems (GIS) award for its use of mapping software from ESRI Ireland.

[26] Due to the pandemic and its impact, the airport lost 115 routes, as in January 2021, it scheduled flights to just 85 cities, down from 200 before the crisis began.

[32] As it is illegal to operate a drone within 5 kilometers of an Irish airfield,[33] DAA called for the Garda Síochana to introduce a counter-drone system and for the government to increase sentences for offenders.

[35] In 2007, Etihad Airways began operating between Dublin Airport and Abu Dhabi, and increased its capacity to 14 weekly flights in March 2010.

In 2015, Ethiopian Airlines began serving Dublin from Addis Ababa, thus inaugurating the first direct air link between Ireland and Sub-Saharan Africa.

This resulted in the immediate cancellation of the long-running 'Shannon Stopover' requirement, whereby the Irish government had insisted that 50% of all transatlantic flights between Ireland and the United States must pass through Shannon Airport.

Those traveling on nonstop flights to the United States complete immigration and customs procedures in Dublin prior to their departure, and are treated as domestic passengers on arrival.

A car park was originally located on the upper floor of the building and the access ramps are still in place but it was closed for security reasons in the 1970s and converted into offices.

Aer Lingus is the main carrier operating at Terminal 2 and since its opening have developed a hub at Dublin primarily for traffic traveling between Europe and the United States.

The Office of the Revenue Commissioners provide a customs service to both passenger and cargo terminals, while the Department of Agriculture also has a presence in the airport.

[55] The construction of a new control complex was required, as the location, height and visibility of the existing tower would be inadequate to operate the planned 10L/28R Runway.

[56] After a delay of several years due to the global financial crisis and predictions of falling consumer demand, it was announced in April 2016 that a new runway would start construction in 2017 and to be completed by 2021.

The airport also has invested heavily in extending aprons and creating rapid exit taxiways to derive maximum efficiency from the existing main runway.

In addition, Dublin Bus and Go-Ahead Ireland run local stopping services that serve such residential areas as Santry, Swords, Rathfarnham, Ballinteer, Sutton, Malahide, Beaumont, Harold's Cross, Terenure, Drumcondra, Balbriggan, Skerries, Rush and Portmarnock.

For many years, it was expected that Iarnród Éireann would extend the Dublin Area Rapid Transit (DART) to serve the airport.

The route for the line, initially known as Metro North, was announced in October 2006 and was proposed to connect with several other modes of transport.