FROM BLOEMFONTEIN TO PRETORIA After their defeats in Natal and the Southern Free State, the Boers slowly adopted a new strategy whereby mobile mounted commandos would be used to wage war over large distances. A defensive stance would only be adopted as little as possible and the British would be attacked from the rear because of the larger opportunity of success. From then on the commandos moved so fast that the British never were quite certain where to look for them. Lord Roberts resumes the Offensive The second phase of the second British offensive consisted of a march along the railway leading from Bloemfontein to the north. Several British columns would protect Roberts' main column from attacks by the Boers. In all the columns consisted of about 100 000 men, while Buller with his 50 000 men would begin an offensive in Natal to join Roberts' forces in Transvaal. The plains of the Free State offered little opportunity to the Boers to use the terrain to stop the British advance. On 12 May 1900 Kroonstad, which served as the Free State capital after the Free State Government evacuated Bloemfontein, fell into British hands. Thereupon the Free State Government moved to Heilbron. In view of the advancing British columns, the Boers then agreed that the Transvaal commandos would fall back ahead of the British advance while the Free Staters would move to the east. Johannesburg On his way northwards from Kroonstad Lord Roberts experienced little opposition. His forces began crossing the Vaal River on the 27th of May. On the 29th the Boers made an effort to stop the advance south of Johannesburg.They however had to evacuate their positions as soon as the British began with their outflanking manoeuvre which Roberts used so successfully since he took over command. Johannesburg was occupied by the British forces on the 31st of May 1900. Pretoria Lord Roberts was under the impression that if Pretoria fell, the Republican armies would lay down arms.He therefore pressed onwards from Johannesburg. Botha decided not to defend the city and ordered the retreat of his commandos along the Delagoabay railway line. President Paul Kruger left Pretoria at the same time On the 5th of June 1900 Roberts entered Pretoria unhindered and presumed that the war would be over. The Republican forces were however far from surrendering. In the Free State for instance the Boers achieved victories at the battle of Biddulphsberg and forced a British Garrison to surrender at Lindley. Gen. De Wet realising the importance of the railway line, as a supply line to the British in the north, began focussing his attention on the railway line. On 7 June 1900 he attacked Rooiwal Station where a large amount of supplies was piled up. This pile up was caused by the destruction of the railway bridges by the Boers. De Wet seized the goods and hid it. For a long time thereafter his commando thus had supplies. De Wet's actions in the Free State caused Roberts to assemble a number of strong British forces in the eastern Free State. These forces drove the Boers to the mountains at Fouriesburg. Here they were surrounded by the British. Although a few thousand Boers managed to slip through the British lines, 4000 Boers under Gen. M. Prinsloo were forced into surrender. Prinsloo's capture, like that of Cronje, had a negative effect on the morale of the Boers. In an effort to stop De Wet, Roberts ordered several drives to capture him. None of these drives were successful because he time and time again managed to evade the British that were on his tail. When after the capture of Pretoria the Boers made no effort to surrender, Roberts had to continue the war by capturing the rest of Transvaal. East, north and west of Pretoria there still were Boer commandos that had to be dealt with. On 11 June the battle of Donkerhoek or Diamond Hill ensued. The Boers under command of Botha stood their ground but, because of a British superiority in numbers, had to retreat. The threat of encircling, that Buller's advance from Natal held, made Botha fall back along the railway line to the east. In August Buller's forces met up with those of Roberts. On 21 August 1900 the Boers and the British engaged in battle again. The battle of Dalmanutha only ended after the 27th of August when the Boers retreated. This was the last conventional or trench battle of the War. By 24 September the whole of Transvaal south of the Delagoa Bay railway was under British control. Mafeking was relieved by the British on 17 May 1900, and very soon al the important towns in Western Transvaal were in their hands too.