Complex sentence: George Eastwood responded with a letter defending the authenticity of the items he was selling, and then by suing the publishers of the "Athenaeum" for libel, even though he had not been named in their report.
Split into simpler sentences: George Eastwood responded with a letter defending the authenticity of the items he was selling. He then sued the publishers of the "Athenaeum" for libel, even though he had not been named in their report.