Battle of Spottsylvania-Hancock's position-assault of Warren's and Wright's corps-upton promoted on the field-good news from Butler and SheridanThe Mattapony river is formed by the junction of the Mat, the Ta, the Po and the Ny rivers, the last being the northernmost of the four. It takes its rise about a mile south and a little east of the Wilderness Tavern. The Po rises south-west of the same place, but farther away. Spottsylvania is on the ridge dividing these two streams, and where they are but a few miles apart. The Brock Road reaches Spottsylvania without crossing either of these streams. Lee's army coming up by the Catharpin Road, had to cross the Po at Wooden Bridge. Warren and Hancock came by the Brock Road. Sedgwick crossed the Ny at Catharpin Furnace. Burnside coming by Aldrich's to Gates's house, had to cross the Ny near the enemy. He found pickets at the bridge, but they were soon driven off by a brigade of Willcox's division, and the stream was crossed. This brigade was furiously attacked; but the remainder of the division coming up, they were enabled to hold their position, and soon fortified it. About the time I received the news of this attack, word came from Hancock that Early had left his front. He had been forced over to the Catharpin Road, crossing the Po at Corbin's and again at Wooden Bridge. These are the bridges Sheridan had given orders to his cavalry to occupy on the 8th, while one division should occupy Spottsylvania. These movements of the enemy gave me the idea that Lee was about to make the attempt to get to, or towards, Fredericksburg to cut off my supplies. I made arrangements to attack his right and get between  him and Richmond if he should try to execute this design. If he had any such intention it was abandoned as soon as Burnside was established south of the Ny. The Po and the Ny are narrow little streams, but deep, with abrupt banks, and bordered by heavily wooded and marshy bottoms-at the time we were there-and difficult to cross except where bridged. The country about was generally heavily timbered, but with occasional clearings. It was a much better country to conduct a defensive campaign in than an offensive one. By noon of the 9th the position of the two armies was as follows: Lee occupied a semicircle facing north, north-west and north-east, inclosing the town. Anderson was on his left extending to the Po, Ewell came next, then Early. Warren occupied our right, covering the Brock and other roads converging at Spottsylvania; Sedgwick was to his left and Burnside on our extreme left. Hancock was yet back at Todd's Tavern, but as soon as it was known that Early had left Hancock's front the latter was ordered up to Warren's right. He formed a line with three divisions on the hill overlooking the Po early in the afternoon, and was ordered to cross the Po and get on the enemy's flank. The fourth division of Hancock's corps, Mott commanding, was left at Todd's when the corps first came up; but in the afternoon it was brought up and placed to the left of Sedgwick's-now Wright's-6th corps. In the morning General Sedgwick had been killed near the right of his intrenchments by rebel sharpshooters. His loss was a severe one to the Army of the Potomac and to the Nation. General H. G. Wright succeeded him in the command of his corps. Hancock was now, nine P. M. of the 9th of May, across the left flank of Lee's army, but separated from it, and also from the remainder of Meade's army, by the Po River. But for the lateness of the hour and the darkness of the night he would have attempted to cross the river again at Wooden Bridge, thus bringing himself on the same side with both friend and foe. The Po at the points where Hancock's corps crossed runs nearly due east. Just below his lower crossing — the troops crossed at three points — it turns due south, and after passing under Wooden Bridge soon resumes a more easterly direction. During the night this corps built three bridges over the Po; but these were in rear. The position assumed by Hancock's corps forced Lee to reinforce his left during the night. Accordingly on the morning of the 10th,  when Hancock renewed his effort to get over the Po to his front, he found himself confronted by some of Early's command, which had been brought from the extreme right of the enemy during the night. He succeeded in effecting a crossing with one brigade, however, but finding the enemy intrenched in his front, no more were crossed. Hancock reconnoitred his front on the morning of the 10th, with the view of forcing a crossing, if it was found that an advantage could be gained. The enemy was found strongly intrenched on the high ground overlooking the river, and commanding the Wooden Bridge with artillery. Anderson's left rested on the Po, where it turns south; therefore, for Hancock to cross over-although it would bring him to the same side of the stream with the rest of the army-would still farther isolate him from it. The stream would have to be crossed twice in the face of the enemy to unite with the main body. The idea of crossing was therefore abandoned. Lee had weakened the other parts of his line to meet this movement of Hancock's, and I determined to take advantage of it. Accordingly in the morning, orders were issued for an attack in the afternoon on the centre by Warren's and Wright's corps, Hancock to command all the attacking force. Two of his divisions were brought to the north side of the Po. Gibbon was placed to the right of Warren, and Birney in his rear as a reserve. Barlow's division was left south of the stream, and Mott of the same corps was still to the left of Wright's corps. Burnside was ordered to reconnoitre his front in force, and, if an opportunity presented, to attack with vigor. The enemy seeing Barlow's division isolated from the rest of the army, came out and attacked with fury. Barlow repulsed the assault with greater slaughter, and with considerable loss to himself. But the enemy reorganized and renewed the assault. Birney was now moved to the high ground overlooking the river crossings built by our troops, and covered the crossings. The second assault was repulsed, again with severe loss to the enemy, and Barlow was withdrawn without further molestation. General T. G. Stevenson was killed in this move. Between the lines, where Warren's assault was to take place, there was a ravine grown up with large trees and underbrush, making it almost impenetrable by man. The slopes on both sides were also covered with a heavy growth of timber. Warren, before noon, reconnoitred his front twice, the first time with one and the second with two divisions. He was repulsed on both occasions, but gained such information of the ground as to induce him to report recommending the assault.  Wright also reconnoitred his front and gained a considerably advanced position from the one he started from. He then organized a storming party, consisting of twelve regiments, and assigned Colonel Emory Upton, of the 121st New York Volunteers, to the command of it. About four o'clock in the afternoon the assault was ordered, Warren's and Wright's corps, with Mott's division of Hancock's corps, to move simultaneously. The movement was prompt, and in a few minutes the fiercest of struggles began. The battle-field was so densely covered with forest that but little could be seen, by any one person, as to the progress made. Meade and I occupied the best position we could get, in rear of Warren. Warren was repulsed with heavy loss, General J. C. Rice being among the killed. He was not followed, however, by the enemy, and was thereby enabled to reorganize his command as soon as covered from the guns of the enemy. To the left our success was decided, but the advantage was lost by the feeble action of Mott. Upton with his assaulting party pushed forward and crossed the enemy's intrenchments. Turning to the right and left he captured several guns and some hundreds of prisoners. Mott was ordered to his assistance but failed utterly. So much time was lost in trying to get up the troops which were in the right position to reinforce, that I ordered Upton to withdraw; but the officers and men of his command were so averse to giving up the advantage they had gained that I withdrew the order. To relieve them, I ordered a renewal of the assault. By this time Hancock, who had gone with Birney's division to relieve Barlow, had returned, bringing the division with him. His corps was now joined with Warren's and Wright's in this last assault. It was gallantly made, many men getting up to, and over, the works of the enemy; but they were not able to hold them. At night they were withdrawn. Upton brought his prisoners with him, but the guns he had captured he was obliged to abandon. Upton had gained an important advantage, but a lack in others of the spirit and dash possessed by him lost it to us. Before leaving Washington I had been authorized to promote officers on the field for special acts of gallantry. By this authority I conferred the rank of brigadier-general upon Upton on the spot, and this act was confirmed by the President. Upton had been badly wounded in this fight. Burnside on the left had got up to within a few hundred yards of Spottsylvania Court House, completely turning Lee's right. He was not aware of the importance of the advantage he had gained, and I, being with the troops where the heavy fighting was, did not know of  it at the time. He had gained his position with but little fighting, and almost without loss. Burnside's position now separated him widely from Wright's corps, the corps nearest to him. At night he was ordered to join on to this. This brought him back about a mile, and lost to us an important advantage. I attach no blame to Burnside for this, but I do to myself for not having had a staff officer with him to report to me his position. The enemy had not dared to come out of his line at any point to follow up his advantage, except in the single instance of his attack on Barlow. Then he was twice repulsed with heavy loss, though he had an entire corps against two brigades. Barlow took up his bridges in the presence of this force. On the 11th there was no battle and but little firing; none except by Mott who made a reconnaissance to ascertain if there was a weak point in the enemy's line. I wrote the following letter to General Halleck:
And also, I received information, through the War Department, from General Butler that his cavalry under [August V.] Kautz had cut the railroad south of Petersburg, separating Beauregard from  Richmond, and had whipped [D. H.] Hill, killing, wounding and capturing many. Also that he was intrenched, and could maintain himself. On this same day came news from Sheridan to the effect that he had destroyed ten miles of the railroad and telegraph between Lee and Richmond, one and a half million rations, and most of the medical stores for his army. On the 8th I had directed Sheridan verbally to cut loose from the Army of the Potomac and pass around the left of Lee's army and attack his cavalry and communications, which was successfully executed in the manner I have already described.