Josef Jakobs, who was a German citizen, was born in Luxembourg in 1898. During the First World War, he served in the German infantry, rising to the rank of Leutnant, in the 4th Foot Guards. In June 1940, ten months after the outbreak of the Second World War, Jakobs was drafted into the Wehrmacht as an Oberleutnant. However, when it was discovered that he had been imprisoned in a Swiss prison from 1934-37 for selling counterfeit gold, he was forced to resign his commission in the Wehrmacht. Jakobs was demoted to a feldwebel (NCO) and placed in the Meteorologischen Dienst (meteorological service) of the Heer. Shortly afterwards, he also began working for the Abwehr, the intelligence department of the German Army. On 31 January 1941, Jakobs was flown from Schiphol Airport in the Netherlands to Ramsey in Huntingdonshire. He parachuted from the aircraft and landed in a field near Dove House Farm, but broke his ankle during the process. The following morning, Jakobs attracted the attention of two farmers, Charles Baldock and Harry Coulson, by firing his pistol into the air. Baldock and Coulson notified members of the local Home Guard who quickly apprehended Jakobs. He was caught still wearing his flying suit and carrying £500 in British currency, forged identity papers, a radio transmitter, and a German sausage.

Josef Jakobs was taken to Ramsey Police Station before being transferred to Cannon Row Police Station in London, where he gave a voluntary statement to Major T.A. Robertson of MI5. Due to the poor condition of his ankle, Jakobs was transferred to Brixton Prison Infirmary for the night. The following day he was briefly interrogated by Lieutenant Colonel Stephens of MI5 at Camp 020 before being transferred to Dulwich Hospital where he remained for the next two months. Jakobs’ court martial took place in front of a military tribunal at Duke of York’s Headquarters in Chelsea, London SW3, on 4–5 August 1941. The trial held was in camera because the German agent had been apprehended in a highly classified intelligence operation known as the Double Cross System. The British were aware that Jakobs was coming because his arrival information had been passed on to MI5 by the Welsh nationalist and Abwehr double agent Arthur Owens. After a two-day trial which involved hearing the testimony of eight witnesses, Jakobs was found guilty of spying and sentenced to death.

Josef Jakobs’s execution took place at the miniature rifle range in the grounds of the Tower of London on 15 August 1941. He was seated blindfolded in a brown Windsor chair. Eight soldiers from the Holding battalion of the Scots Guards, armed with .303 Lee–Enfields, took aim at a white cotton target (the approximate size of a matchbook) pinned over Jakobs’ heart. The squad fired in unison at 7:12 a.m. after being given a silent signal from Lieutenant-Colonel C.R. Gerard (Deputy Provost Marshal for London District). Jakobs died instantly. A subsequent postmortem examination found that one bullet had hit Jakobs in the head and the other seven had been on or around the marked target area. Following the execution, Jakobs’ body was buried in an unmarked grave at St. Mary’s Roman Catholic Cemetery, Kensal Green, London. The location used for Jakobs’ grave has since been re-used so the original grave site is difficult to find. All other German spies condemned to death in the UK during the Second World War were executed by hanging at HM Prison Wandsworth in South London. Jakobs was the last person to be executed at the Tower of London.