Complex sentence: James Fintan's brother Richard born in 1823, was himself to become a Young Irelander, and who later supported Parnell, becoming an M.P for Queen's County from 1880 until 1892.
Split into simpler sentences: James Fintan's brother Richard born in 1823, became a Young Irelander who later supported Parnell. He was an M.P for Queen's County from 1880 until 1892.