Washington, Sopt. 1. The following rebel dispatehes werè received this luorning: Charleston, Aug, 25, The enemy' huid batteries'havo been maintatning a stedy fire on Sumpter all d:iy, l'ighting at Wagncr was' chiefiy oonfined to tlio firing of bur piokets on the encmy's sapper's, who continue to approaeh Wagner. This ëvening about duik Ihe encniy's butterics opcncJ a furious fii-f on Wagner. preparatory, aswas supposed. to the afsault'" The foilowiiig offioiiil dispatfhes have just been roei'ived : "Fort Sunipter' 7:35 P. M. There is an assault now being made at Battery Wagner. (Siguod) "ALFRED RHETT, "Cdloiu'l CoiuinaiHiüii;." Fort Johnson, Aug. 23, 7:45 P. M. " ïhs enemy is aasaulting Battery Wagner, ovidmtly n heavy force. (Signed) "C. II. ABM8TB6, "(Joloiii! Coimnandiiüi." ' later.- Musketry has ceased, but tbc eueiuy ia firing a few morUr shulls at Wanner. The h'rst assauit has been repulsed. No more sheüs have been thrown at the eily since day-light on Moiiday morning."