May – Appearance in court of men and women charged under Explosive Substances Act 1883 in a Birmingham courtroom. They were charged with belonging to an IRA team working from "the headquarters in the Midlands for manufacturing incendiary and explosive bombs". 5 May In Liverpool, tear gas bombs exploded in two cinemas, causing 15 injuries. In Coventry, four bombs exploded. In London, two bombs exploded. 13 May - In London, three explosions occurred in Underground (train) stations. 16 May – Arrests made and seizure of 8 lbs of potassium chlorate, two powder fuses, 12 26 and a half sticks of gelignite, two sticks of saxonite, fuses, a revolver and ammunition, twenty-nine balloons, and street maps of Salford, Manchester and Liverpool. An unexploded bomb, found abandoned on a bus, was identified with this material when the arrests were made. 18 May – Two men sentenced to 10 and 15 years penal servitude for possession of 10 bundles of gelignite, a 5-pound pack of gelignite, 103 detonators, and 4 balloons. 19 May Eight timed incendiary bombs caused fires to break out in eight British hotels. Eight arrests made in Birmingham in connection with an explosion at a house in Manchester. 29 May – In Birmingham, four magnesium charges exploded in the Paramount Cinema. 30 May – IRA "General Call to Arms" sounded, with hundreds of IRA members running from house to house collecting gas masks and burning around 1,000 in heaps in 15 streets. 30 May – In Liverpool and Birmingham, magnesium and tear gas bombs exploded during the evening show in cinemas. Twenty-five people had to be taken to hospital but no material damage was done. 31 May – Seanad Éireann (the Irish Senate) approved the Offences against the State Act, and it was put into effect after being signed by President Douglas Hyde. 31 May – In London, cinemas were attacked with incendiaries, prompting the police to search every London cinema. June 7 June – In Detroit, USA, Seán Russell was arrested at the request of Scotland Yard. He had been conducting a speaking tour as part of the propaganda arm of the S-plan. 9 June – Letter bombs exploded in twenty postboxes. One went off in a London sorting office and another in a Birmingham mail lorry. Every postbox in London was searched for further IRA devices. 10 June – In London, Birmingham and Manchester, bombs exploded in thirty