Bryan, Daniel (‘Dan’) (1900–85), soldier and intelligence officer, was born at Dunbell, Co. Kilkenny, on 9 May 1900, the eldest of the twelve children of John Bryan, farmer, of Dunbell, and his wife, Margaret Mary (née Lanagan), of Maddoxstown, Co. Kilkenny. Educated at the CBS Kilkenny, he entered UCD in 1916 and spent two years studying medicine. In November 1917 he joined the Irish Volunteers and served in C and G companies, 4th battalion, Dublin brigade. He participated in raids, armed patrols, and observation work (he was a scout on Baggot Street Bridge during Bloody Sunday, 21 November 1920), and in January 1921 was appointed assistant battalion intelligence officer, working with Sean Dowling, Sean MacCurtain, and F. X. Coughlan. His duties included the correlation of intelligence derived from Tommy Daly (qv), an employee of the Kildare Street Club. He never fired a weapon in anger during his long revolutionary and military career, and never commanded a battalion, the usual route to senior rank in the army. Intelligence was his métier.
In June 1922 Bryan joined the national army as an officer on the general staff. He became heavily involved in intelligence work during the civil war, and his agents, who were widely feared, were instrumental in the wide-scale arrests of anti-treatyites in the Dublin area. Partly in order to facilitate clandestine meetings with agents, Bryan developed the habit of working on his own late at night. This, along with being teetotal and a non-smoker, probably contributed to his somewhat solitary persona in the army. On 4 September 1923 he was promoted to the rank of captain, and the following year officially moved to the intelligence branch, where he was to the fore in uncovering the army mutiny. To Bryan the mutiny was essentially about ‘whiskey and jobs’.
In 1926 the army's role in the gathering of domestic intelligence was terminated and Bryan was transferred to the defence plans division (October 1927–November 1928). In 1927 he attended the five-year-review conference of the treaty defence arrangements in London, and in October 1930, while working in the assistant chief of staff's branch, he attended the imperial conference in London. He was acting director of the intelligence branch, designated G2, in 1931. Despite his loyalty to the Free State, he maintained informal contacts within the republican and labour movements and is credited with snuffing out the wild talk of malcontented officers who boasted that they would refuse to take orders from a Fianna Fáil government should one be elected.
Bryan graduated in June 1933 from the infantry officer's course. While on the command and staff officer's course (September 1934–July 1935), he incurred the wrath of Major-General Hugo McNeill (qv) by writing a thesis that contradicted the latter's military strategy. Bryan argued that the state did not have the means to resist an external attack, and pointed to the threat that a foreign power might use Ireland and encourage the republican movement for the purposes of gathering intelligence and causing trouble in Britain. This became the basis of ‘Fundamental factors affecting Irish defence policy’, circulated to ministers in May 1936, which was the first official document to shed light on the internal security implications of the Irish policy of neutrality. It assessed Ireland's security position in relation to Great Britain and rejected the thinking of a group of senior officers who envisaged successfully taking on the British military in time of war, and pointed out that Ireland was not virtually ‘but absolutely disarmed’.
After returning to G2 in 1935 with the rank of major, Bryan was one of the team that briefed Éamon de Valera (qv) on the state's defences prior to the negotiations that led to the handing over by Britain of the treaty ports in 1938. In that same year primary responsibility for security intelligence was transferred to G2, where Bryan established a defence security section to address the problem of German use of Ireland for intelligence activities directed against Britain and France. He was appointed deputy director (1938–41) and promoted to colonel. From 1939 he established excellent working relations with the head of MI5's Irish desk, Cecil Liddell, and with Liddell's powerful brother Guy (who rose to be head of counter-espionage and deputy director of MI5 by 1945). When Bryan became director of G2 in July 1941 relations improved further. Liddell had found Bryan's predecessor frustrating to deal with on the sharing of information relating to the activities of German nationals and the German legation in Ireland. Bryan admired Lieutenant-General Dan McKenna (qv) (unexpectedly appointed chief of staff after the dismissal of Michael Brennan (qv)), not for his direct and sometimes brutal manner, but for the relentless drive and decisiveness which he exhibited in expanding and professionalising the defence forces. McKenna, in turn, left Bryan to his own devices, while providing support by meeting Cecil Liddell and other British officers.
Bryan enjoyed intelligence work for its own sake, and his enthusiasm and good relations with Liddell led to increased cooperation as the war progressed. He worked closely with the secretary of the Department of External Affairs, Joseph Walshe (qv), de Valera's key foreign policy adviser, and with the assistant secretary, F. H. Boland (qv). These links meant that Bryan's actions carried the taoiseach's imprimatur, and left him unusual leeway in the management of intelligence liaison. On 11 November 1941 Bryan visited London at the invitation of MI5 to discuss the activities of both the German legation and the agent Herman Goertz (qv). Despite Ireland's neutrality, he arranged for a British wireless expert to visit Dublin in an attempt to find the signal of the German legation. Bryan also agreed that the Irish army's signal corps would provide the British with reports of all transmissions intercepted from the German legation and arranged to keep a twenty-four-hour watch on the legation itself.
In collaboration with the Department of Posts and Telegraph's special investigation unit and the Garda aliens and security sections and special branch, G2 developed an impressive counter-intelligence network. In 1940 Bryan secured a key informant within a covert intelligence organisation established in Ireland by the British Secret Intelligence Service, and G2 were thus able to monitor its information-gathering activities until the end of the war. By the end of 1943 the Irish had netted all twelve Abwehr agents sent to Ireland, mostly within a few days of each one's arrival, including the elusive Herman Goertz. Bryan brought in Dr Richard Hayes (qv), director of the NLI and an amateur cryptographer, in an attempt to crack the cipher used by Goertz. Liddell later described Hayes's gift in this area as amounting ‘almost to genius’. Bryan was not informed for some time that Hayes had cracked the Goertz code, as Colonel Eamon de Buitléar (1902–81), a linguist foisted upon Bryan as second in command who had little aptitude for intelligence work, unilaterally withheld this information because he believed that Bryan would hand it immediately to the British authorities. This breakthrough caused considerable excitement in MI5 and the British code-breaking service. The cipher cracked by Hayes was used by the British to decode intercepted messages carried to the German legation in Lisbon by a man named Eastwood, a ship's cook who was working for a charlatan and would-be agent, Joseph Andrews. The messages ultimately indicated that the general officer commanding of the second division of the Irish army had been in contact with Goertz, but this was never disclosed. General Hugo McNeill, whom Bryan distrusted, often tried to bypass and belittle him, and to interfere in intelligence work.
In combination with other elements of the defence forces, G2 also developed effective air and coastal observation and wireless interception systems which were crucial to the maintenance of neutrality and the provision of information to the Allied powers (de Valera believed that the more such material Ireland provided, the less could the Allies claim to be seriously damaged by Irish neutrality). After the war Bryan unsuccessfully opposed the dismantling of the G2 security apparatus, but the Department of Justice, with which he had fraught relations during the Emergency, argued successfully that the Garda security section and special branch should be restored to primacy. Bryan then concentrated his energies on investigating communism in Ireland and its foreign links, partly on the basis that if the Irish did not do this, the British and American agencies would establish a covert presence in Ireland. Much to Bryan's annoyance, Seán MacBride (qv), minister for external affairs (1948–51), was obsessed by the notion of pervasive British espionage. Bryan was disappointed not to be appointed adjutant general of the army, feeling that he had been unfairly tainted in Fine Gael eyes by his wartime links to de Valera's closest advisers, but in truth his talents and experience lay mainly in intelligence, where he was peerless.
Bryan was a member of the Irish military delegation that visited the US army's European command in November 1951. He was moved from G2 and appointed commandant of the Military College in March 1952 (in later years, former cadets remembered him as an amiable but distant figure). In November 1955, seeing his promotion hopes again frustrated by the inter-party government, he took early retirement.
Bryan was a founder member of the Military History Society of Ireland (1949) and, with the support of Dr Michael Tierney (qv) and Professors G. A. Hayes-McCoy (qv) and R. W. Dudley Edwards (qv), unsuccessfully argued for a chair of military history at UCD. A deeply religious and rather conservative man, who retained a strong Kilkenny accent, he looked more like a professor than a spy master, and was modest, discreet, and humane about personal failings. Douglas Gageby (qv) (1918–2004), who served in G2 (1944–5), spoke of his formidable intellect, and of the steel which lay beneath his mild appearance and manner of constantly blinking while thinking. His absent-mindedness about inessentials was well known in the army and even in British and American intelligence agencies. In his last years he was inclined to be discursive in talking with researchers, but his prodigious memory and unerring ability to identify links between apparently unrelated episodes and individuals remained to the end.
In 1930 Bryan married Ellen Barton-Fraser, of Ballsbridge, Dublin, who predeceased him by some years. They had no children. He died 16 June 1985 in Dublin after briefly suffering from stomach cancer, and was buried in the local church near his family home at Dunbell, Co. Kilkenny. His unpublished memoirs (IE UCDA P109) as well as his papers (IE UCDA P71) are deposited in the UCD archives, while some of his correspondence with MI5 is in the NAI (A3, A8/1, and A60).