Hermann Görtz (also referred to as Goertz in English) (15 November 1890 – 23 May 1947) was a German spy in Britain and Ireland before and during World War II, liaising with the Irish Republican Army (IRA). After the war, he committed suicide rather than be deported from Ireland to Germany.
Hermann Görtz was born in the port city of Lübeck in northern Germany in 1890. Few details are available about his war service, but it is thought he fought on the Eastern Front against Russia before being wounded around Christmas 1914, later receiving the Iron Cross for valour. At some point during the war he joined the German Air Force. He trained as a pilot and served as a reconnaissance officer, but after he showed a talent for "interrogation" of captured enemies, he was promoted to the rank of Captain as an interrogations officer by the end of the war. Görtz served alongside Hermann Goering, who would go on to become head of the Luftwaffe. The most notable moment in Görtz's first military career seems to have come after the Armistice - it was said he was responsible for persuading Goering not to burn the planes in his squadron before the enemy forces impounded them.
Following the war, Görtz returned to civilian life and married Ellen Aschenborn, the daughter of a German Admiral. Görtz threw himself into education and earned a doctorate in international law, something which lead to him frequently travelling abroad. It was during a trip to Ireland in 1927 that he developed an affection for the country. The visit may have been part of a study of the legal relationships forming between Ireland and the United Kingdom at that time. Görtz was known to show an interest in Irish politics; during conferences in America Görtz would converse with members of Clan na Gael, an Irish republican group based in the United States who leant against the Anglo-Irish Treaty. Görtz sympathised, viewing the treaty in the same light as the treaties imposed upon Germany at the time. 
Hermann Görtz arrived in Britain on 29 August 1935 with a secretary, Marianne Emig. They spent a few weeks in Suffolk and eventually moved to Broadstairs and rented a house. There they befriended British airman Kenneth Lewis and through him began to collect information about the RAF Manston air base. Emig asked for letters of Royal Air Force stationery and photographs of the planes and aerial views. When Lewis became concerned that he might be passing military information, she assured him that Britain and Germany would be on the same side in the next war. Lewis later testified that he was surprised at how much the couple already knew about the RAF.
Near the end of their six-week tenancy, Görtz visited Germany and telegraphed his landlady Mrs Johnson that he would be gone for two days and asked her to take care of his belongings in the outhouse, including his "bicycle combination". Görtz had meant his overalls, but Mrs Johnson thought he was referring to his Zündapp motorcycle. Mrs Johnson checked the outhouse, did not find the motorbike and reported to police that it had disappeared. When police investigated the apparent theft, they found sketches and documents about Manston airfield.
When Görtz returned to Britain three weeks later, police arrested him at Harwich. Emig had stayed behind in Germany.
Görtz was detained in Brixton prison. Police accused him of offences against the Official Secrets Act (effectively for espionage). The trial at the Old Bailey began in March 1936 and attracted much publicity. Görtz pleaded not guilty and claimed the documents were part of his research for an intended book about the enlargement of the British Air Force. He intended to write the book to pay off his creditors. Marianne Emig refused to come to Britain to testify for Görtz' defence, fearing that she would be tried as well.
According to evidence, including letters Görtz had sent his wife, it appeared that Görtz had been acting independently, possibly to impress the German intelligence service. He had already unsuccessfully applied for a position in the German Air Ministry. Further evidence also showed that he had been involved in the interrogation of Allied prisoners at the end of World War I.
Görtz was convicted and sentenced to four years of prison for espionage and sent to Maidstone Prison. In February 1939, he was released and deported to Germany. German military intelligence eventually did employ him and he reached the rank of major.
In the summer of 1940, Görtz parachuted into Ballivor, County Meath, Ireland (Operation Mainau) in an effort to gather information. He moved in with former IRA leader Jim O'Donovan. His mission was to act as a liaison officer with the IRA and enlist their assistance during a potential German occupation of Britain. However, he soon decided that the IRA was too unreliable. On landing, he lost the 'Ufa' transmitter he had parachuted with. Goertz, attired in a Luftwaffe uniform, then walked to Dublin. He was not apprehended despite calling into a Garda barracks in Co Wicklow, asking for directions to Dublin. Goertz made it to Dublin and a "safe-house" at 245 Templeogue Road, Templeogue. He also stayed in a number of other properties during his 19 months at liberty. These include houses in Spencer Villas, Glenageary; Charlemont Avenue, Dún Laoghaire; Nerano Road, Dalkey; Winton Avenue, Rathmines; and a period house in Shankill, Co. Dublin. He stayed for a month at Brittas Bay, and more briefly at Laragh Castle, Glendalough, Co Wicklow, Fenit, Co Kerry and Mount Nugent, Co Cavan.
In May 1940, the Gardaí raided the home of an IRA member of German descent, Stephen Carroll Held, who had been working with Görtz, at his house at Blackheath Park, Clontarf. They confiscated a parachute, papers, Görtz's World War I medals, and a number of documents about the defence infrastructure of Ireland. The papers they took included files on possible military targets in Ireland, such as airfields and harbours, as well as detailed plans of the so-called "Plan Kathleen". This was an IRA plan for the invasion of Northern Ireland with the support of the Nazi military. Held had brought this plan to Germany prior to Görtz's departure but his superiors had dismissed it as unfeasible.
Görtz went into hiding, staying with sympathizers in the Wicklow area and purposefully avoided contact with IRA safehouses. He remained at large for a total of eighteen months. When another IRA member, Pearse Paul Kelly, visited Goertz's hiding place in Dublin in November 1941, police arrested them both.
Hermann Goertz was released from prison in Athlone in August 1946. He went to live in Glenageary and became secretary of the Save the German Children Society. He was rearrested the following year and served with a deportation order by the Minister for Justice. He claimed to have been in the SS rather than a lieutenant in the Luftwaffe in an attempt to prevent his deportation but this claim was disproved by Irish Military Intelligence (G2) which also "promoted" him to Major when sending him messages allegedly from Germany. On Friday 23 May 1947 he arrived at the Aliens' Office in Dublin Castle at 9.50 am and was told he was being deported to Germany the next day. Although it had been stated to him that the Irish government had specifically requested that he not be handed over to the Soviets, he committed suicide.
The Irish Times reported that he: "Stared disbelievingly at the detective officers. Then suddenly, he took his hand from his trouser pocket, swiftly removed his pipe from between his lips, and slipped a small glass phial into his mouth. One of the police officers sprang at Goertz as he crunched the glass with his teeth. The officer got his hands around Goertz's neck but failed to prevent most of the poison, believed to be prussic acid, from passing down his throat. Within a few seconds, Goertz collapsed." He was driven to Mercer's Hospital and died there shortly after arrival.