Rudolf Cornelis Leonhard served as a male nurse [Verpleger] with the 1st Ambulance of the Dutch Red Cross in South Africa.
‘The personnel of the First Dutch Red Cross Ambulance comprised Doctor G. Lingbeek (leader), Prof. J. Korteweg, Doctors Romeyn, Oidtmann, Bierens de Haan, and Vinckhuijzen, ten nursing sisters (all from Amsterdam), and four male nurses, including R. C. Leonhard. At Rietfontein, Dr Bierens de Haan took over the clinic and Dr Lingbeek was in charge of the outpatient clinic, but as it became clear that one doctor could manage at Rietfontein on his own, Dr Lingbeek with male nurses Leonhard and Bos, went to General Erasmus’s laager. They established a small field hospital using their cumbersome Amsterdam ambulance wagon that was of no use for patient transport but provided excellent accommodation for the staff. The masterly inactivity for which this general had gained considerable renown ensured that they had very little work to do, particularly as far as surgery was concerned.
In September  Dr Bierens de Haan, his assistant Leonhard and three volunteers left Hectorspruit with their refurbished ambulance to accompany Commandant General Louis Botha to the Northern Transvaal. Bierens de Haan apparently reported on this expedition in his letters to the Dutch Red Cross Society but the official report he submitted was lost so that relatively little is known about this spell of two months (September to November 1900) that he spent in the northern Transvaal.’ (Helpers, Healers and Hospitals, by J. C. (Kay) de Villiers, refers)
Sold with copied Vorm “B” and extracts from the above publication which gives a good account of the First Dutch Red Cross Ambulance with several more mentions of Leonhard.