And what challenges did they face both internally and externally in the Abolitionist Movement?

The Abolitionist Movement had noble goals, and it was a movement that put the humanity in front the profit, which was very good and a huge step forward.

That didn't passed very well with lot of people though. Very large portion of the people were not willing to give up on their free labor force, thus lose big chunk of their profit if they had to pay the laborers. The racism was still at a very high level, and lot of people still looked at the slaves as people that are primitive, and as lower beings, so they were not very fond of the idea to have equal rights with them.

The problems were both inside the countries, and also international, as there were people in all countries that were for and against the movement, as well as some countries being for while other countries being against the movement's goals. That led to multiple conflicts, mostly external, but also raised the tensions between numerous countries with different opinions on the matter.