Final answer:
Mother Mary Harris Jones was sent to arrest the Hatfields and bring them to trial in Kentucky during the Paint Creek-Cabin Creek Strike in West Virginia in 1912.
Step-by-step explanation:
The person who was sent into West Virginia to arrest the Hatfields and bring them to trial in Kentucky was a union organizer named "Mother" Mary Harris Jones. She was arrested and imprisoned, along with many other labor organizers, during the Paint Creek-Cabin Creek Strike in West Virginia in 1912. The state government, acting on behalf of the coal operators, used heavy-handed tactics to suppress the unionization efforts of the miners. The federal government eventually launched an official investigation into the actions of the state government, marking a turning point in the history of states' rights versus federal authority.