Montgomery's plan for Eighth Army's night attack at Alamein (Operation Lightfoot) on 23/24 October required XIII Corps to penetrate the enemy's two belts of minefields (codenamed 'January' and 'February') and then pass the armoured brigades through. For 22nd Armd Bde this involved an approach march of and then an advance of through four gaps, with its flank covered by 131st Infantry Bde. The Royal Engineers' mine-clearing parties moved forward when the artillery barrage began at 21.40 and had cleared the two southern gaps through 'January' by 02.30, but 1st RB's two advance guard companies had to subdue enemy post before the northern gaps could be completed. By 05.00 5th RTR and the two 1st RB companies were through 'January' by one gap or another, but the mine-clearing parties had suffered heavy casualties; they could only attempt two gaps through 'February', and these were frustrated by heavy fire and daylight. 22nd Armoured Brigade's casualties during the night were 200. The following morning the tanks had to sit in open formation under steady shellfire.