For a fortnight this underground struggle continued, and then Don Frederick--finding that no ground was gained, and that the loss was so great that even his bravest soldiers were beginning to dread their turn to enter upon a conflict in which their military training went for nothing, and where so many hundreds of their comrades had perished--abandoned all hopes of springing a mine under the walls, and drew off his troops. A month had already elapsed since the repulse of the attack on the breach; and while the fight had been going on underground a steady fire had been kept up against a work called a ravelin, protecting the gate of the Cross. During this time letters had from time to time been brought into the town by carrier pigeons, the prince urging the citizens to persevere, and holding out hope of relief. These promises were to some extent fulfilled on the 28th of January, when 400 veteran soldiers, bringing with them 170 sledges laden with powder and bread, crossed the frozen lake and succeeded in making their way into the city. The time was now at hand when the besieged foresaw that the ravelin of the Cross gate could not much longer be defended. But they had been making preparations for this contingency. All through the long nights of January the noncombatants, old men, women, and children, aided by such of the fighting men as were not worn out by their work on the walls or underground, laboured to construct a wall in the form of a half moon on the inside of the threatened point. None who were able to work were exempt, and none wished to be exempted, for the heroic spirit burned brightly in every heart in Haarlem. Nightly Ned went down with his aunt and cousins and worked side by side with them. The houses near the new work were all levelled in order that the materials should be utilized for the construction of the wall, which was built of solid masonry. The small stones were carried by the children and younger girls in baskets, the heavier ones dragged on hand sledges by the men and women. Although constitutionally adverse to exertion, Frau Plomaert worked sturdily, and Ned was often surprised at her strength; for she dragged along without difficulty loaded sledges, which he was unable to move, throwing her weight on to the ropes that passed over her shoulders, and toiling backwards and forwards to and from the wall for hours, slowly but unflinchingly.