As General Burnside’s army concentrated on the north bank, General Lee’s forces concentrated on the heights in the rear of Fredericksburg. Had the pontoon bridges been at hand when the advance reached Falmouth, the line of the Rappahannock would have been taken without opposition. Then, with proper supplies and bridges, thirty of the sixty miles to Richmond would have been placed within the reach of General Burnside, and perhaps a lodgment have been effected on the banks of the North Anna. Nearly thirty days elapsed before the pontoons arrived and the bridges were completed. It was the design of General Burnside that the pontoons should leave Alexandria on November 11, and arrive at Falmouth at the same time with the advance of his army. The right grand division reached Falmouth on November 17. The pontoons left Alexandria on November 19, and arrived at Fredericksburgh after the movements of General Burnside had not only become known, but after General Lee had advanced his forces from Gordonsville to the heights in the rear of Fredericksburg, and had fortified them. They were not used until the night of December 10, owing to material changes in the plan of the commander-in-chief, necessitated by new movements of the enemy. During the night of the 10th of December, therefore, the pontoons were conveyed to the river, and the artillery to the number of one hundred and forty-three pieces was placed in position opposite the city. Between four and five o’clock on the morning of the 11th, the work of building four bridges was commenced. One was to be made at the point where the railroad bridge formerly crossed, and two others opposite the city but nearer Falmouth, and the fourth nearly two miles below for the crossing of the left wing under General Franklin. A dull haze so obscured the movement, that it was not discovered for some time by the Confederate pickets. The bridges were thus partly constructed, when a brisk and deadly fire of musketry from along the banks of the river and windows of the houses was opened, which compelled the workmen to stop. They fled to the cover of the surrounding hills where they formed again, and about six o’clock the work was recommenced. The Confederates had now become aroused to a sense of what was going forward, and with reinforcements of sharpshooters swarmed the opposite bank and houses. The pontonniers, nothing daunted by the hot fire poured upon them, went bravely to work. A storm of bullets covered them. The planks and boats were riddled by every volley. Once more they were compelled to withdraw, and again fell back to the cover of the ridge of hills running parallel with the river. Orders were now given to the artillery to open fire on the city. The Federal batteries commenced an almost simultaneous bombardment, directing their fire chiefly at the houses in which the sharpshooters had concealed themselves. At the first fire they became untenable, and