There was a long halt at Bloemfontein, and during this period enteric fever proved a ter rible scourge to the British, and the Boers were encouraged to fresh activity. Several mishaps now befell different bodies of British troops, and De Wet proved himself a leader of excep tional ability on the Boer side, while Louis Botha (q.v.) also gained distinction for himself, having succeeded to the chief command on the death of Joubert (27 March). The advance northward from Bloemfontein began on 3 May. The British forces under Gens. Ian Hamilton, French and Pole Carew, with Lord Roberts at their head, often showed a front of 40 miles, and though the enemy repeatedly seemed to threaten a determined stand, no effective re sistance was encountered, either on the Vaal or elsewhere. One after another the Boer posi tions were turned; Botha's troops fled in con fusion from Johannesburg; where the British flag was hoisted on 31 May, and Pretoria, the Transvaal capital, was occupied on 5 June; no attempt being made by the Boers to hold the forts. General Botha and a considerable body of men retired eastward along the railway in the direction of Komati Poort, near the Portu guese frontier, in which direction President Kruger, Mr. Reitz and other members of the Transvaal government had preceded him. The Boers were followed and beaten at Pienaar's Poort, about 15 miles from Pretoria. Mean while Buller had been advancing northward through Natal, and had entered the Transvaal from that side, driving the Boers before him. On 15 May Dundee and Glencoe were retaken, on the 17th Newcastle, and by the end of the month he was encamped within striking dis tance of Majuba and Laing's Nek, which were strongly held by the enemy. But by a skilful turning movement General Hildyard secured command of the Boer positions, which were at once evacuated. Buller's force had marched 50 miles in six days, and had defeated the Boers in four engagements. His troops were thus put in a position to co-operate with the main army under Lord Roberts, and early in July the rail way to Pretoria from Durban was open. The number of British troops in South Africa by the middle of the year was about 250,000.
Shortly after the middle of May (1900) news reached England that the Boers had been driven from Mafeking, and that the town had been entered by a British force from the south. The place had been invested from 15 October, when Cronje with a force of some 9,000 men had marched to the attack. It was well sup-, plied with stores, and this, together with the indomitable energy and fertility of resource shown by Major-General Baden-Powell, who commanded the small garrison, enabled it to hold out against all attempts to capture it. A last attempt to take it had been made on 13 May by Commandant Eloff, a grandson of President Kruger. This not only failed, but the leader and a number of his men were themselves taken prisoners.
In the end of July an important success was gained in the Orange Free State (now called Orange River Colony) by General Hunter, with the aid of Generals Rundle, Clement, Bruce Hamilton, Paget and Macdonald. As the result of a combined movement, a force of some 4,000 Boers under Prinsloo was surrounded by the British troops and forced to surrender with guns, horses and wagons, the burghers being sent as prisoners to Ceylon. De Wet, with
2,000 men, escaped, as on various subsequent occasions.
Advancing eastward from the Pretoria dis trict Roberts joined hands with Buller, and from his headquarters at Belfast issued a proc lamation annexing the Transvaal to the British dominions (1 September). Previous to this Buller had forced the Boers from a strong position they had taken up near Machadodorp, and had thus effected the release of a large number of prisoners whom they had taken with them from Pretoria.
On 11 September President Kruger took refuge in Portuguese territory, and many of his compatriots followed his example, or scattered in different directions, having previously de stroyed many of their guns, with vast quantities of ammunition and stores. Lord Roberts re ported that there was nothing left of the Boer armies but a few marauding bands, but this view of the case proved premature. On 6 October Buller left the army for England; on the 20th President Kruger sailed for Europe on board a Dutch man-of-war. Lord Roberts left for home before the end of the year, hand ing over the chief command to Lord Kitchener.
The war had now entered upon what might be called the guerrilla stage, during which the activity and daring of such leaders on the Boer side as Botha and De Wet gave plenty of hard work to the British troops. Looking with con fidence for support from their kinsmen in the Cape Colony and Natal, and still hoping for the intervention of some European power, the Boer leaders planned two enterprises which they thought might yet retrieve their cause. Botha, with some 6,000 men, was to make a sudden dash into Natal and raid the country, if pos sible, all the way down to Durban, while De Wet was to execute a similar movement in the direction of Cape Town. These attempts were made in the early part of 1901. Botha's plan was completely frustrated by a great sweeping movement of General French; the Boers were dispersed with the loss of guns, wagons and immense numbers of cattle and sheep. De Wet fared no better but, like Botha, he himself es caped capture, though losing guns, ammunition and wagons. Marauding bands that had be longed to his force managed, however, to enter the Cape Colony, and for a time gave much tmuble, aided and encouraged as they were by their Dutch friends. To checkmate the Boer system of warfare Kitchener resolved to clear the country of food and cattle so as to deprive the Boers of supplies, to protect the railways by chains of blockhouses, to carry similar chains across the country in suitable directions, and to keep the Boers perpetually on the move by mobile columns of British troops. Kitchener's measures, which were found exceedingly effect ive in the long run, included the gathering to gether of great multitudes of Boer women and children into the so-called concentration camps, a measure widely discussed and much con demned in the press of neutral countries.