11 June 1900
On 11 June, 1900, Boer commandos and British forces clashed at Donkerhoek (Diamond Hill) during the South African War. The battle came after General Lord Roberts, Commander of the British forces met with no resistance when they entered Pretoria on 5 June. Roberts thought that the war would soon be over, but the Republican forces proved to be far from surrendering. Elsewhere in the Free State, the Boers achieved victories at the battle of Biddulphsberg. Subsequently, a British Garrison was forced to surrender at Lindley. The war continued for another two years before a treaty was signed in Vereeniging in 1902, paving the way for the establishment of the Union of South Africa in 1910.
References

Melrose House, ‘From Bloemfontein to Pretoria’, [online], available at www.melrosehouse.co.za (Accessed: 15 May 2012)|Tswanetourist,(2011) ‘Diamond Hill aka Donkerhoek’, 06 October [online], available at https://tshwanetourist.wordpress.com(Accessed: 15 May 2012)