 In 1881 Mathews ' old vessel , the HMS London , was captained by Charles J Brownrigg . This vessel and her crew made several patrols aimed at hindering the slave trade using smaller steam boats for the actual <unk> and captures . On December 3 , 1881 , they caught up with a slave dhow captained by Hindi bin <unk> . This dhow had around 100 slaves on board and was transporting them between Pemba and Zanzibar . Captain Brownrigg led a boarding party to release the slaves but bin <unk> 's men then attacked the sailors , killing Brownrigg and his party before sailing away . Mathews led a force to <unk> on Pemba and , after a short battle , took a mortally wounded bin <unk> prisoner before returning to Zanzibar . 
