Yet the disaster was not due to his default alone, although the contributory defaults of others were rightly not permitted to excuse him. He had good reason to think that a well-mounted force would be able to take care of itself, and to believe that proper staff arrangements had been made for Spragge's march; but in each of these warrantable assumptions he was wrong. Lindley was the first of a series of disasters which seemed to show that Lord Roberts had pushed on too hastily. Rundle's endeavour to help Spragge by a demonstration in the direction of Bethlehem soon came to an end. It is said that a telegram in which he announced the movement to Brabant fell into the hands of the Boers, who promptly utilized the information. On May 29 he was seriously checked at the Biddulphsberg, where they had taken up a position. He failed in an attack on what he believed was the Boers' flank but which was in reality their front. During the engagement he received a telegram from Head Quarters, dated three days previously, ordering him to join Brabant in the Ficksburg district, and he withdrew from the action, having suffered 186 casualties, some of which were caused by a fire which broke out in the long grass through which he had advanced, and in which helpless wounded men were lying. A brigade of Tucker's Division under Clements took his place at Senekal. De Wet now set himself in person to execute the task entrusted to him by Botha of getting behind the British force in the Transvaal and breaking or interrupting the line of communication in the Free State. He had not long to wait for opportunities. He left Frankfort with 800 men, and on June 2 placed himself in observation near Heilbron, where Colvile was awaiting a supply column from the railway at Roodeval. The convoy was harassed from the first by mischances. Against Colvile's orders it was despatched with but a small escort and without guns. When he heard that sufficient protection could not be given, he counter-ordered the convoy, but the message did not arrive until after it had started. On the second day of the march a body of the enemy was found blocking the road at Zwavel Kranz between Heilbron and Heilbron Road Station. It was De Wet waiting for the convoy. The news of its plight reached Heilbron Road Station,[45] and a relieving column was sent out, which came within four miles of Zwavel Kranz. No firing, however, was heard, and the officer in command, hastily concluding that all was well, returned to the railway without finding the convoy, which next morning surrendered, the victim of easy-going indifference and neglect.