The German Plot
Introduction from Chronology
Sinn Féin leaders arrested (including de Valera, Plunkett, Griffith and MacNeil) on charges of conspiracy with Germany – known as the "German Plot". Even though Sinn Féin knew about their imminent arrests, quite a few decided to let themselves be arrested to gain political capital.
This was the first action of French as Lord Lieutenant. There was little evidence produced that Sinn Féin leaders were in communication with the Germans. Seventy-three of those arrested were deported and imprisoned in Britain. When French publishes his ‘evidence’ on May 25th, it is not well received even in Westminster.
McMahon says that it was the Special Branch of the London Metropolitan Police (under Basil Thomson); the Intelligence Section of the British Navy (under Admiral Reginald ‘Blinker’ Hall) and the British Security Service or MI5 (in particular one of its senior officers Major Frank Hall ‘a classic Ulster imperialist’) who produced a “steady stream of alarmist information on German intrigues in Ireland, which the London intelligence chiefs replayed to British ministers and the Dublin Castle executive … and therefore produced warnings that the [British] government felt obliged to act on”.
McMahon goes on to say that “when the British government was unable to produce convincing evidence of a ‘German Plot’, nationalist Ireland concluded that it had been invented as retribution for the defeat of conscription”. McMahon concluded “The measure backfired dramatically”.