Complex sentence: The survivors of Bligh's open-boat journey gave evidence against their former comrades--the testimonies from Thomas Hayward and John Hallett were particularly damaging to Heywood and Morrison, who each maintained their innocence of any mutinous intention and had surrendered voluntarily to "Pandora".
Split into simpler sentences: The survivors of Bligh's open-boat journey gave evidence against their former comrades. The testimonies from Thomas Hayward and John Hallett were particularly damaging to Heywood and Morrison; each maintained his innocence of any mutinous intention, and each had surrendered voluntarily to "Pandora".