* Martin will become "Primate of All Ireland"
* Brady was hit by sexual abuse scandal
By Philip Pullella
VATICAN CITY, Jan 18 (Reuters) - Pope Benedict on Friday appointed the new head of the Roman Catholic Church in Ireland to succeed Cardinal Sean Brady, whose tenure has been plagued by scandal over the sexual abuse of children on the predominantly Roman Catholic island.
The Vatican said Monsignor Eamon Martin, 51, had been named "coadjutor" archbishop of Armagh, meaning he will automatically succeed Brady when he retires next year.
Brady, who will remain primate until his retirement, has resisted calls by three of the four main parties in the Republic of Ireland and Northern Ireland's deputy first minister to resign over the sexual abuse scandal.
The Vatican's move was seen as an attempt to give him a soft exit. While it spared him the embarrassment of stepping down before his scheduled retirement, he will effectively be sidestepped as Martin takes over the running of the diocese.
Armagh, which is in Northern Ireland, is a particularly significant diocese because its archbishop has the title "Primate of All Ireland," the senior Church position on the divided island.
A BBC television documentary last year reported that Brady failed to warn parents their children were being sexually abused by a priest in 1975 after he had been given the information by one of the victims.
The abuser, Father Brendan Smyth, died in 1997, just one month into a 12-year sentence after pleading guilty to 74 charges of indecent and sexual abuse of boys and girls for more than 30 years.
Brady apologised at the time of the documentary but said it was misleading.
The Church in Ireland, where for centuries religion was embedded in the national psyche, has been rocked by a series of reports of child sex abuse stretching back decades and of leaders' complicity in covering them up.
Ireland last year closed its embassy to the Vatican, one of its oldest diplomatic missions, after relations hit an all-time low over the abuse scandals.
"I am saddened that many good Catholics were let down so badly over the issue of abuse and that some have even stopped practising their faith," Martin said in a statement about his appointment.
"As Church, we must continue in our efforts to bring healing to victims and ensure that young people are always protected, respected and nurtured," he said.
A Vatican report last year accused the island's religious leaders of negligence and called for more reforms there to avoid a similarly "shameful" scandal in the future.
Years of crisis over sexual abuse have included several damning government reports, the resignations of several Irish bishops and a papal letter to Irish Catholics.
As in other countries, Catholic leaders were accused of turning a blind eye to sexual abuse and shuttling clergy accused of abuse from parish to parish instead of defrocking them or turning them in to police. (Reporting By Philip Pullella; Editing by Angus MacSwan)