Among the individuals you mentioned, John Mensah Sarbah and J.P. Brown played active roles in the colonization of Northern Ghana by the British.
John Mensah Sarbah was a prominent lawyer, writer, and politician in the late 19th century. He was an influential figure in the Gold Coast (modern-day Ghana) and advocated for the interests of the indigenous people. Sarbah played a significant role in resisting British colonial rule and was one of the founders of the Aborigines' Rights Protection Society, which aimed to protect the rights of the local population.
J.P. Brown, whose full name was Joseph Phillip Brown, was a British colonial administrator who served in the Gold Coast during the colonial period. He held various positions within the colonial administration, including District Commissioner and Resident Commissioner. Brown was involved in implementing British policies and exerting British control over the region, including the northern parts of Ghana.