1901 Boer War FPO 28 to England (Canadian H. A. C. Machin)

1901 Field Post Office 28 British Army S. Africa (OC 28 01), countersigned by himself as officer at lower left “From H. A. C. Machin Lieut/ SAC/ Vet River”, to Ida Knight in Sydenham, England with purple triangle “Passed Press Censor” and rated 1d FBB, “T” hs. Reverse with London transit (NO 23 01). It is most peculiar that he wrote Vet River indicating where he was located. I think most Boer War collectors would agree that this practice is highly unusual. Has anyone ever seen this practice before?

Harold Arthur Clement Machin was born in Rochester, NY in 1875, educated in England, studied law at Osgoode Hall and called to the bar, setting up a law firm in Rat Portage in 1898. He was a member of the 12th York Ranger, and recruited in Toronto to the Royal Canadian Regiment, 1st Contingent, “C” Company. His service number was #7369 and served as a private. He sailed from Quebec on Oct. 20, 1899, landing in Cape Town on Nov. 30. He was promoted to Sergeant and saw action in several battles including Sunnyside, Paardeberg, Poplar Grove, Driefontein, Hout Neck, Vet River, Zand River, and Pretoria. He returned to Canada with “C” company on December 23, 1900. He received his commission as a Lieutenant in the South African Constabularly in March 1901, returning to South Africa. He was promoted to Captain and based in Bloemfontein, capital of the Orange River Colony (ex-Orange Free State). He corresponded with Ida Knight in England, who would eventually move to Cape Town and marry Machin in 1902. He served until the end of the war in May, 1905 and retained his rank, awarded the Queen’s Medal (South Africa) with four clasps, and the King’s medal (South Africa) with two clasps. They returned to Kenora, Ontario where he continued to work as a lawyer, and later as an MPP from 1908-1919. He served in WWI in a labour batallion, was the director of the Military Services branch of the Canadian Department of Justice, responsible for enforcing the Miltary Services Act (conscription). He investigated the anti-conscription riots in Quebec and advised Prime Minister Borden to impose martial law. He was a fierce opponent of temperance. Machin township in Kenora is named after him.
References: Wikipedia, Globe and Mail, Kenoreagreatwarproject.ca, military service records.