Complex sentence: Russell set up spring camp at Shillelagh, hunting and fishing and receiving the heads of rebels, but O'Byrne was elusive and he intrigued with Hugh O'Neill, Earl of Tyrone.
Split into simpler sentences: Russell set up spring camp at Shillelagh, hunting and fishing and receiving the heads of rebels. But O'Byrne was elusive, even as he intrigued with Hugh O'Neill, Earl of Tyrone.