In the 1950s, the IRA launched a campaign of attacks on Northern security targets along the border (the Border Campaign). The Irish government first detained the IRA's leaders under the Offences Against the State Act and later introduced internment for all IRA activists. This helped to halt the campaign in its tracks, and the IRA called it off in 1962. In the aftermath of this episode, the southern government under Seán Lemass, himself an IRA veteran of the War of Independence and Civil War, tried to forge closer ties with the authorities in Northern Ireland to promote peaceful co-operation on the island. He and Northern premier Terence O'Neill exchanged visits, the first of the respective heads of state to do so since the very early days of partition in 1922.