From: Brandfort
This Prisoner of War record for Martinus Wilhelmus Siebert was transcribed record from various documents held at the National Archives, South Africa, including arrest and shipping information from newspaper sources like De Zuid-Afrikaan.
https://www.gendatabase.com/boer-war-prisoner-record.php?q=13457&r=Martinus Wilhelmus&s=Siebert&ref=
This set of Prisoner of War documents can be accessed online via the FamilySearch.org project by Clicking Here.
