by the Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij (NZASM), until that railway was itself seized by the Imperial Military Railways (IMR) by the end of the same year. With these locomotives being the only mainline engines to actually see service on the PPR, and with the railway only being in existence for five months before it was taken possession of by the NZASM, it was not officially classified. For lack of a classification, they are referred to as , since the NZASM also classified its own locomotives according to their weight. Imperial Military Railways At the outbreak of the war, control of all railways in the Cape of Good Hope and Colony of Natal was taken over by the invading British military. It was operated by the IMR, which was established on 7 October 1899 upon the appointment of Lieutenant Colonel E.P.C. Girouard KCMG DSO RE as Director of Railways for the South African Field Forces. While Girouard largely left control of the Cape Government Railways (CGR) and the Natal Government Railways (NGR) in the hands of the civilian staff, the railway lines of the Oranje-Vrijstaat Gouwerment-Spoorwegen (OVGS) in the Orange Free State and of the NZASM and its recently seized PPR in the ZAR came under the IMR's control as possession was obtained of their lines. The replacement sixth locomotive was delivered to the IMR in 1900 and became the new no. 6. Central South African Railways Hostilities ceased on 1 June 1902. On 1 July 1902, the IMR was transferred to civilian control and became the Central South African Railways (CSAR). These six locomotives were taken onto its roster, designated the CSAR's Class D and renumbered in the range from 209 to 214. During 1904, all six locomotives were upgraded by the CSAR by having their cylinder diameter increased by , which improved their hauling capacity by 15%. This resulted in the engines being able to haul the same load as a 7th Class locomotive. South African Railways When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, NGR and CSAR) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January