Answer:
Frederick Douglas was already a member of the Northampton Association of Education and Industry which was an abolitionist movement. Sojourner Truth who was a lady got to join the movement later and she was known to be hosted by President Lincoln due to her continual persistence to gain the required audience.
They were however the most effective abolitionists of the mid 1800s due to their level of persistence in ensuring that the blacks were treated equally.
They also helped blacks settle down and into the American system after the War.