Why would Captain Parker order the militamen “take care of themselves” and go home?

Answer/ Explanation:
Captain Parker told his men instead to disperse and go home, but, because of the confusion, the yelling all around, and due to the raspiness of Parker's tubercular voice, some did not hear him, some left very slowly, and none laid down their arms. Both Parker and Pitcairn ordered their men to hold fire, but a shot was fired from an unknown source.