The initial Naval Brigade was composed as follows:
Commander Ethelston of H.M.S. 'Powerful' in command.
Major Plumbe, R.M.L.I., of H.M.S. 'Doris' 2nd in command.
9 Naval officers.
53 bluejackets.
7 Marine officers.
290 N.C.O.'s and men of the Royal Marines.
The guns were two 12-pounder 8-cwt. guns on ordinary field mountings.
This brigade served in Natal and was later increased in size. It is this larger Brigade composed as follows which were present at the battles you are interested in:
Commander Ethelston of H.M.S. 'Powerful' in command.
Major Plumbe, R.M.L.I., of H.M.S. 'Doris' 2nd in command.
9 Naval officers.
53 bluejackets.
7 Marine officers.
290 N.C.O.'s and men of the Royal Marines.
The guns were two 12-pounder 8-cwt. guns on ordinary field mountings.
The Royal Marines manned some of the guns or escorted and supported them.
You should read Naval Brigades in the South African War by Jeans available on the Books section of this website.