As Roberts's army occupied Pretoria, the Boer fighters in the Orange Free State retreated into the Brandwater Basin, a fertile area in the north-east of the Republic. This offered only temporary sanctuary, as the mountain passes leading to it could be occupied by the British, trapping the Boers. A force under General Archibald Hunter set out from Bloemfontein to achieve this in July 1900. The hardcore of the Free State Boers under De Wet, accompanied by President Steyn, left the basin early. Those remaining fell into confusion and most failed to break out before Hunter trapped them.