Complex sentence: The mutiny, which broke out during the return voyage on 28 April 1789, was led by Christian and supported by eighteen of the crew, who had seized firearms during Christian's night watch and then surprised and bound Bligh in his cabin.
Split into simpler sentences: The mutiny, which took place on 28 April 1789 during the return voyage, was led by Christian and supported by eighteen of the crew. They had seized firearms during Christian's night watch and surprised and bound Bligh in his cabin.