and the election of a parliament to which the Provisional Government will be responsible. 11 February – Clones Affray (County Monaghan): gun battle at Clones railway station between IRA volunteers and members of the Ulster Special Constabulary travelling to Belfast; five killed. 12 February – at the launch of the Republican Party, Éamon de Valera says that the Treaty denies the sovereignty of the Irish people. 17 February – existing British postage stamps issued with overprint Rialtas Sealadach na hÉireann 1922. 18 February – Liam Forde, Officer Commanding the Irish Republican Army Mid-Limerick Brigade, proclaims that it no longer recognises Collins's authority. February – the Civic Guard – predecessor of the Garda Síochána – is established as a police force to replace the Royal Irish Constabulary in areas outside Dublin and Ulster. March–April 22 March – senior officer Rory O'Connor declares that the Irish Republican Army will no longer obey Dáil Éireann. 1 April The British Government orders the release of all Irish prisoners in British prisons convicted of sedition. The Irish Post Office takes over responsibility for its own operations. 26–28 April – Dunmanway killings: Thirteen Protestant men, suspected of involvement as or with informants to the British Army, are killed in and around Dunmanway, County Cork. 14 April – Rory O'Connor, with 200 other anti-Treaty Irish Republican Army men under his command, occupies the Four Courts building in the centre of Dublin in defiance of the Provisional Government. 26 April – the Irish Catholic Church hierarchy implores the people of Ireland to accept the Treaty and to make the best of the freedom which it brings. May–June 4 May – a conference at the Mansion House, Dublin, between both sections of the Irish Republican Army secures a three-day truce. 15 May – the Civic Guard Mutiny begins in Kildare. 16 May – the final group of British troops leave the Curragh Camp. 19 May – the Irish Republican Army, with Collins's covert support, attempts to launch a "Northern Offensive" in Ulster. 20 May – a "pact" between de Valera and Collins provides that Sinn Féin contest election as a single party 22 May – two hundred men, all Catholics, are arrested and interned under the Special Powers Act after a period of public disorder and the murder of a member of the Parliament of Northern Ireland, mostly on HMS Argenta prison ship moored in Belfast Lough. They include