Up to this time, Lord Roberts was acting without the cavalry under French, who since the Sannah's Post affair had been working in the Thabanchu district, and who joined the main column on May 9. Though his horses were not in good condition, his arrival increased the power of the centre to strike rapidly at the next obstacles, the Zand River and the town of Kroonstad forty miles beyond, which was now the seat of the Free State Government. The drifts on a section of the river nearly twenty miles in length were seized, the most easterly being taken by Ian Hamilton, who had gradually converged on the centre column and was now on the right of the line. Next day the passage of the river was effected; but Lord Roberts' hope of getting round and grappling each flank of the enemy, who numbered about 3,000 Transvaalers and 5,000 Free Staters, was not realized, and Botha withdrew without serious loss. That night the Army went into bivouac astride the railway between Zand River and Kroonstad. On the left was the cavalry under French, who next morning raided northwards; but although he was unable, owing to the opposition of a force which came out of Kroonstad, to reach the railway north of the town, a small party of pioneers whom he had sent on succeeded during the night in blowing up the line at America Siding within a few yards of the high-road by which the enemy was retreating. This daring exploit, which although it had not much effect on the situation was not the less meritorious, was carried out by Hunter-Weston, who, just two months previously, had similarly cut the line north of Bloemfontein. The Boers had taken up a position at Boschrand to defend Kroonstad on the south, but French's turning movement scared them, and the position as well as the town was abandoned, in spite of efforts made by Steyn and Botha to arrest the flight. The seat of Government was transferred to Lindley. The Zand River affair was an incident in the advance rather than a battle. Lord Roberts suffered but 115 casualties. Its effect on the enemy was chiefly moral. The Transvaalers, whose country had not yet heard the sounds of war, were alarmed, but the Free Staters were dismayed. The ties of race and kindred had engulfed them in a war which was not for their own cause, and the brunt of which they had borne for ten weeks. They thought that they had done all that could be expected of them and that the Transvaal must now look after itself. From that time there was no organized co-operation between the allies.