Complex sentence: Released under partial amnesty of March, 1869, because of ill-health, and upon his release Kickham was made Chairman of the Supreme Council of the I.R.B. and, according to Devoy, "the unchallenged leader" of the reorganized movement.
Split into simpler sentences: Released under partial amnesty of March, 1869, because of ill-health. Upon his release Kickham was made Chairman of the Supreme Council of the I.R.B. and, according to Devoy, "the unchallenged leader" of the reorganized movement.