This picture was taken during General Botha's campaign against the Germans in South-West Africa. There had been some concern as to how loyal the Boers might be against the Germans when World War One broke out. After all, the Boers had only been defeated by the British just over a decade earlier. There were some issues and reluctance on behalf of the Boers initially, but surprisingly some of their former generals came to play an incredibly important role in the British war machine both in Africa and back in Europe.
This particular picture shows Botha's forces relaying train track which had been destroyed by retreating German colonists in South West Africa. In an era before reliable road transport, trains were a vital means of military and civil communication. Much of the fighting took place along train lines or in attacking the bridges and telegraph wires that travelled alongside them.