How was gambia imperialism?

Gambia was the place from where most slave transports to the Americas started, so the ownership of its trading station was regularly and hotly disputed among Britain and France and the fort changed hands at least ten times. It was Britain that managed to hang on to it in the end. After Britain abolished the slave trade in 1807, it actively patrolled the west African coast to catch slave ships and free the slaves found there. They also worked hard to end slavery in Gambia (and elsewhere in Africa) by Africans themselves. But it took until 1906 until Gambia itself abolished slavery.