On May 2 Lord Roberts informed Buller that he was ready to start from Bloemfontein, and that he expected the Natal Army to co-operate with him by attacking the Boers on the Biggarsberg, and then advancing towards the Transvaal.  For this movement Buller considered that his force, which consisted of three divisions of infantry and three brigades of mounted troops, in all about 45,000 men, was insufficient; but he proceeded to carry it out.  The Boers were in occupation of the whole line of the Biggarsberg from Helpmakaar westwards, and commanded the roads as well as the railway running through the range.

Buller on this occasion determined rightly upon a turning movement.  All his previous attacks had either been frontal or had been made so by the enemy.  His plan was to move eastwards with the IInd Division under Clery, while the Vth Division under Hildyard, who succeeded Warren when the latter was called away to Bechuanaland, advanced up the railway against the Boer centre.  The IVth Division under Lyttelton, composed of the infantry which had been in Ladysmith during the siege, was kept in reserve pending the development of the turning movement, which began on May 11, and was skilfully conducted by Buller and was entirely successful.  Places and rivers which had not been named in the chronicle of the war since October of the previous year now emerged from their obscurity.  Elandslaagte became the fulcrum of an aggressive operation.  Sunday’s River and the Waschbank River after an interval of seven months were again crossed by British troops, not, like Yule’s force, in hasty retreat, but in confident advance.

The Boers prepared for, and fully expected, a direct advance on Beith by way of Van Tender’s Pass, but Buller made for the extreme flank of the range near Helpmakaar, which they held but lightly.  It was rendered untenable on May 13, and after dark they retired on Beith, setting fire to the veld to mask the movement and hinder pursuit.  At dawn Dundonald pushed on through the flames and smoke with his mounted infantry, but was checked by a body of Irish traitors who were acting as rearguard to their flying employers, and was unable to come up with the burghers.  On the following night his patrols reported that Dundee was clear, and Buller occupied the town and reached Newcastle on May 18.  The success of the turning movement was due in a great measure to a small force under Bethune, which had been lying for some months lower down the Tugela, and which Buller called up to threaten Helpmakaar from the south while he advanced from the west.  It had been originally detached to protect his right flank during the advance on Ladysmith, and after long inaction as a watching force was restored to the strenuous campaign.