P. S.Lieutenant Kerin, my adjutant-general, who accompanied the advance to the Chickahominy, informs me he saw no sign of wagon or gun tracks on that road. The guns must have been turned back at Old Church, and the wagons reported to be with them were probably among those burned. I think it proper to state, what I have omitted in my report to Gen- eral Reynolds, that the enemy left the hospital at Baltimore Cross-Roads at 2 oclock in the night and committed no depredations on the hospi- tal. These facts I had in person from the intelligent surgeon in charge. W. H. EMORY, Brigadier- General. HEADQUARTERS FIRST BRIGADE, CAVALRY RESERVE, Caralry Camp, June 16, 1862. SIR: In obedience to orders received last night I send you my report and the reports of all the officers referred to in that order belonging to this brigade who took a part in expelling the enemy which broke into our lines on the 13th instant. In reference to the first two paragraphs of the order9 requiring the account of the inroad on Captain Royalls camp, I have no knowledge whatever. That officer, with two squadrons, was detached from my command ten days since, with orders to report to General Cooke in person. I was not favored with a copy of his instructions nor the purpose for which he was detached, and neither he nor any of the officers o C his command have made any report to me, officially or unofficially, since they were detached until this time. About 3.30 or 4 oclock in the afternoon of the 13th instant I heard the call to horse sounded from headquarters, which was not repeated at any of the camps. My whole command was, however, speedily in the saddle. Seeing the Fifth in the saddle, I rode to General Cookes head- quarters for instructions. I met his aide-de-camp, who directed me to send forward rapidly the Fifth and Sixth U. S. Cavalry to support Cap. -tam Royall. I gave the order in person to the commander of the Fifth, and sent a message to the Sixth U. S. Cavalry to follow, designing to give the orders to the commander of the Sixth in person as he came up. The Sixth, however, by taking a short cut, got so far ahead that I had to ride 2 miles to communicate with Major Williams, who was in command, and gave him the same instructions that I had given Cap. tam Whitingto push on with all possible speed. At this moment a sergeant, commanding a picket on the road leading north this side of Bethesda Church, informed me the enemys pickets were on that road. I detached Captain Chambliss squadron to observe that road and drive in the enemys pickets. Fortunately Colonel Rush, with his Lancers, had followed on without orders. This enabled me to relieve Captain Chambliss from that duty by a squadron of Lancers and send him with the force to support Captain Royall, and the body of the Lancers was held in reserve near where the roads unite until the force and direction of the enemy could be truly ascertained and until I could communicate with General Cooke. A few moments afterward I met General Cooke coming on at the head of the First U. S. Cavalry. At this moment three important communications arrived: One from Major Williams, telling me he had fonud the enemy in force between himself and Captain Royall (which I handed to General Cooke); one