Map of Pretoria and the region to the east of the city, showing the troop movements of the British and the Boers in the lead up to the Battle of Bronkhorstspruit on 20 December 1880, the first major engagement of the First Boer War. 
The red line shows the movement of the British column, which left Lydenburg on 5 December and passed through Middelburg on their way towards Pretoria to reinforce the British position there. On 20 December, they were intercepted by a Boer commando which had left Heidelberg on 18 December with the express purpose of preventing the British forces reaching Pretoria.
Own work

Movements based on Laband, John (2014) [2005]. The Transvaal Rebellion: The First Boer War, 1880–1881. Abingdon, England; New York, United States: Routledge. ISBN 978-1-317-86846-0, pp. 91–96.
Harrias