The ship was the last vessel to enter service before the merger between the Union and Castle shipping lines in 1900. She served on the South Africa route until the First World War when she was used by the UK as a troop transport, carrying troops of the Australian and New Zealand Army Corps to the Gallipoli Campaign. Galeka was then refitted as a hospital ship with accommodation for 366 wounded passengers.
On 28 October 1916, while entering Le Havre, HMHS Galeka struck a mine. She was not carrying patients at the time, but 19 Royal Army Medical Corps personnel died in the sinking. She was beached at Cap la Hogue, but was a total loss, Union-Castle's first war casualty.