The men in the Federal lines leaped from their hiding places and ran to the parapets in the face of a murderous fire from the defenders of the city, only to be mowed down by hundreds. Others came, crawling over the bodies of their fallen comrades--now and then they planted their colors on the battlements of the besieged city, to be cut down by the galling Confederate fire. Thus it continued hour after hour, until the coming of darkness. The assault had failed. The Union loss was about three thousand brave men; the Confederate loss was probably not much over five hundred. Grant had made a fearful sacrifice; he was paying a high price but he had a reason for so doing--Johnston with a reënforcing army was threatening him in the rear; by taking Vicksburg at this time he could have turned on Johnston, and could have saved the Government sending any more Federal troops; and, to use his own words, it was needed because the men "would not have worked in the trenches with the same zeal, believing it unnecessary, as they did after their failure, to carry the enemy's works." On the north side of the city overlooking the river, were the powerful batteries on Fort Hill, a deadly menace to the Federal troops, and Grant and Sherman believed that if enfiladed by the gunboats this position could be carried. At their request Admiral Porter sent the _Cincinnati_ on May 27th to engage the Confederate guns, while four vessels below the town did the same to the lower defenses. In half an hour five of the _Cincinnati's_ guns were disabled; and she was in a sinking condition. She was run toward the shore and sank in three fathoms of water. The army now settled down to a wearisome siege. For six weeks, they encircled the city with trenches, approaching nearer and nearer to the defending walls; they exploded mines; they shot at every head that appeared above the parapets. One by one the defending batteries were silenced. The sappers slowly worked their way toward the Confederate ramparts. Miners were busy on both sides burrowing beneath the fortifications. At three o'clock on the afternoon of June 25th a redoubt in the Confederate works was blown into the air, breaking into millions of fragments and disclosing guns, men, and timber. With the mine explosion, the Federal soldiers before the redoubt began to dash into the opening, only to meet with a withering fire from an interior parapet which the Confederates had constructed in anticipation of this event. The carnage was appalling to behold; and when the soldiers of the Union finally retired they had learned a costly lesson which withheld them from attack when another mine was exploded on July 1st.