Allied shipping is under continuous danger of attack by German U-boats. However ships also face another danger: each other. In the early hours of the morning the Mendi, a British steamer carrying men from the South African Native Labour Corps is sailing through thick fog in the Channel when it is accidentally rammed by the much larger Darro, a British cargo ship. The Mendi sinks quickly.
Although damaged, the Darro remains afloat, but her captain, Henry Stump, has her sail away as quickly as possible. She does not assist the survivors of the Mendi. The Brisk, a British destroyer, manages to rescue around 200 of the South Africans, but the loss of life from the incident is considerable. All 30 of the Mendi‘s crew lose their lives, as do 616 of the South Africans.
The Mendi in happier days (Wikipedia)