Complex sentence: The British centre column was wrecked and camp annihilated with heavy casualties and the loss of all its supplies, ammunition and transport leaving Chelmsford no choice but to hastily retreat out of Zululand.
Split into simpler sentences: The British centre column was wrecked and its camp annihilated with heavy casualties as well as the loss of all its supplies, ammunition and transport. The defeat left Chelmsford no choice but to hastily retreat out of Zululand.