After the relief of the siege of Mafeking on 17 May 1900 its defender, Robert Baden-Powell, moved towards Pretoria, establishing garrisons and supply depots along the way. One such depot was on the banks of the Elands River where the town of Swartruggens now stands. 300 Australians and 200 Rhodesians manned the post under the command of Colonel C.O. Hore, a veteran of the Mafeking siege. On 3 August, a large convey of wagons arrived from Zeerust and waited at Elands River for an escort before proceeding further to Rustenburg. That night General J.H. de la Rey surrounded the post and at dawn he opened his attack with an initial artillery salvo into a party taking the draft animals to drink at the river. The shells caused havoc in the camp, wounding many of the defenders and killing dozens of oxen and horses. Hore was ill and active defense and leadership devolved on two Australians, Major Tunbridge and Captain Ham, and a Rhodesian, Major Hopper. They rallied the men throughout the day of ceaseless Boer shelling. The British position was hopelessly exposed with little in the way of defensive earthworks and no access to water. Only when night fell was it possible for the men to stealthily take the remaining animals to drink at the river and to dig better defensive trenches into the hillside. Morale was maintained on the British side by the belief that they would be soon relieved by General F. Carrington who was due to arrive from Marico with 650 men and a New Zealand artillery unit.
The following day, when Carrington was only three kilometers way, de la Rey ambushed his relief column and, with only 70 men, chased the entire column back to Marico. Thinking that a far greater force than his own was pursuing him, Carrington burned all the supplies in Marico and continued his flight to Mafikeng, destroying the stores at Zeerust and Ottoshoop as he did so.
Despite their disappointment the beleaguered Australians and Rhodesians refused to surrender. and prepared to endure another day of bombardment. A second rescue attempt by Baden-Powell from Rustenburg also ended in bungling and disaster. As Carrington fled towards Mafikeng Baden-Powell reached Moedwil and, hearing the sound of gunfire retreating westward, assumed that Hoare's men had been relieved. Satisfied with this unsubstantiated assumption Baden-Powell returned to Rustenburg.
The situation at Elands River continued to become more desperate as Boer snipers kept them from collecting water from the river and men were wounded or killed with almost every attempt to do so. Thirst and the stench of the decomposing carcasses of horses and cattle increased their discomfort. Meanwhile a report had reached Lord Roberts in Pretoria that Elands River had surrendered, so no help was forthcoming. Only after a message between Generals De la Rey and De Wet was perchance intercepted was the truth discovered and a strong force under General Broadwood dispatched and the siege was at last relieved on 17 August. The courage of the colonial forces at Elands River is still lauded in the annals of Australian military history and a plaque has been erected by the Australian High Commissioner to commemorate the centenary of the engagement.