Cearbhall Ã `` DÃ laigh ( 12 February 1911 -- 21 March 1978 , ) served as fifth President of Ireland , from 1974 to 1976 . Cearbhall Ã `` DÃ laigh ( 12 February 1911 -- 21 March 1978 ; ) served as the fifth President of Ireland , from 1974 to 1976 .