I have been transcribing the Daily Journal of C Troop Royal Engineers in Zululand From March 1879 to January 1880. Here is a taster.
"Aug. 1st 1879. Six miles of cable were paid out from Landman’s Drift and
Doornberg and an office and heliograph station established
signalling to the Oskerberg over Rorke’s Drift, by which means
Sir Garnet Wolseley who had arrived there, sent all his
messages down and up country."
Hopefully, it might be made available in its entirety at some point.