16 February 1900
The action that culminated with the Boers shelling Rhodesian positions at Basuto Kop on 16 February 1900 can be traced in part by Rhodesian fears that the Boers would attempt to invade Rhodesia. The Boers were also attempting to sever railway lines to Gabarone in order to deny Mafikeng any relief from this quarter while they were besieging it. The positions of the Boers were firstly detected when a Rhodesian patrol came upon Boer positions at Basuto Kop. The Boers however were too preoccupied with shelling the Bridge over the Metsimasauna River to pay much attention to the patrol, and the Rhodesians escaped unscathed. The Rhodesian response was to shell Boer positions from Spitzkop, which led to the Boers withdrawing to Magagbe Hill and fortifying their positions there. This led to a mostly futile attempt by the Boers to continue shelling the positions the Rhodesians had taken up at Basuto Kop.  The Rhodesians in return attempted to dislodge the Boer positions. After a sharp exchange, the Rhodesians were forced to withdraw and the Boers abruptly ceased contact and withdrew to Sepitse Hill.
References

Burret, R.S., Gaborone and the Anglo-Boer War, 1899-1902, from The South Africa Military History Society, [online], Available at samilitaryhistory.org [Accessed: 08 February 2010]