Simplify the following text for a Grade 6 native English-speaking person.
Original: The pair were transferred to Dartmoor Prison on 21 October 1851 , but shortly afterwards Johns was transferred to the Woolwich prison hulk Justitia , probably for disciplinary reasons .
Simplified: On 21 October 1851 , they were sent to Dartmoor Prison . Johns was sent to the Woolwich prison hulk Justitia , probably for bad behavior .