St. Louis, May 10. Gen. Frost's brigade of Missouri militia, encnmped at Camp Jaekson, in the western outskirts of the city, surreiïdercd unconditionally this aftoniooii, ou dejuand of Oapt. Ly n, who tnnrclicd on Camp Jaoksoü with somo 4,000 volunteers, snrrounded it, ;uid plantod eight field-picces on the adjoining eminenees. The Jbllowing letter was sent f rom Gapt, Lyon to Gen. Frost: ITuADftCAJiTíRS U. S. Tuoors, ) St. Louis, May 10, 1861. $ ToGen,D. M. Frot : '■ Sir - Your coimnand is regarded as evidently hostile towards the rovenniient of the United Status. It is for the most part made up of those seeessionists ■who have openly avowed thcir hostility to the general government, uud !:ive been plottiug at the seizuro of it3 property and ovcrtLrow of its authority. You are openly in communioatiou with the socalled Southern Oonfederiicy. wbioh is now at war with the United States, and you are receiving at your e;unp froin snid Confedcracy, and undet its flag, largo Bupplies of materials of war, the most oi' ■which is kuown to be tho property of tbc United States. These extraordinary preparatious. pluinly indic-ate none otlier thnn the veil known purposc of the Governor of tliis State, undcr whoso orders you are acting, and whoso purpose, recent}y coniaiunicated to the Legislature. has just beea responded to by that body in the most uuparalleled legislation, baving in direct view hostilities to the general government and co-oporatiou with its encmiee. In view of these conaiderations, nnd your failure to disperse in obadience to the proclamatiou of the President, and of the erainent neeessity of the State poliey and welfare, aud obligatioas iraposed upon me by instruetions from Washington, it is ray duty to demand, and I do hereby demand, of you au immediate surrender of your conunand, with uo othcr conditious than that all pereons surrendering uuder tliis demand shall be hunianely aud kindly treated, believing myself preparcd to enforce this demand. One-half hour's time before doing so will be allowed for your compliauce therewith. (Signed) N. LYON. Captain 2d Iafantry, coiumanding troop It is undorstood that Oen. Frost says thi letter was not recoived by him until his camp was surrounded by Uni.'.cd States troops. Ile then replied üiat the cncainpment was oxgnmze'J under the law of the Stale, and sitnply for organitiDg and drilling the volunteer militia of this district. ]Sot expecting any demonstration, he was unpreparci to successfully resist aa attack. IIo thertfore accepted the terms speeiüed, and surrendercd his command, about 800 men then in camp, a largo number being in tho city on leave. They then laid down their umn, and were escorted to tho city as prisoners of war. A release on parole was tendered the rtfficera and troops, providing they would tako oath not to takc up arms against the Uuited States govornraent, which tliey declined, on tho ground tbat it uuplied they had already taken up anus ngainst th govcrnmcnt, which they disclahned. Just before the troops started for the city, and while tho State forccs were drawn up betwcen two lines of volunteers, eiveral rocks were thrown at the volunteers, aud a few pistol shots were fired by excitod parties iu the surrounding crowd, wbioh was composed of u large nuinber of citizons ine'uding many woraen. Oue shot took efl'ect in the log of Captain Blentowsky, and, as ho feil, he f ave tho word to fire, which was obeyed y 6oni8 two or three companies, Tesulting JD tho death of upwards of twenty persons, including two womcn and several children, and badly wouading several othcrs. Iuteuso czcitement ex'mts in the city. L.irge bodtes of roeu are thronging the etrects AU tbe gun shops in the city are guarded by armed pólice, and about 200 men have beon detailcd to proteot the Demoerat and Antieger offices. Bt. Louis, Sunday, May 12. Tbc city has scoa another terriblo affair. Last uight, about 6 o'clock, a large body of Home Guards entered the city through Fiftb street frora thearaena], ■whore tbey bad been enlisted during the day, and furnished witb arms. On reachirjg Waluut street the troops turned westward, a large orowd liniug the paveïnonts to witness their progresa. At the corner of Fiftb street partios among tho spectators begau hootiug, bissing, aud otherwiso abusing the companies as they paesed, and a boy about iburteen jearg of ago dischargcd a pistol into the ranks. Part of the rear cotnpany imraediately turnod and fired upou the crowd, aud the wholo column was immediately in con' fusión, breaking tbeir ranks, diseharging musketa down tbeir own line, and araong the people ou. the sidewalks. The shower of baila for a faw minutes was terrible, tho bullets flying in cvery direction, entering doors, windows, private residences, breaking Bhutters levelling ruling, and erea amasbin bricks in third storics. - The utmost coufusion and coa&ternation prerailed', spectaturs fitiug iu all direction-", and but for the randoia firing of tbe troops,8corts of people must havo. been killed, as niot of the ériug was directed (Íowd their own rauks. The troops suffeied most severely, fou.r of tbeir nuuib.er buing instantly killed and several wuun(led. Immense crowds of peoplo filled the etrects. Aftcr tbo occurrence most iufsruw indignation was expressed against the üünaar.s. Mayor Taylor addressed tho ostv.cd crowd aud Induoed them to djgnewe, umlor promise t!iat no further violenee should be done. The city was coiüparntiveiy quiet dnving thQ eveuing and rnght, a Ueavy rain prevent ing thc assciibiing of large crowda. 'J'he ótate troupe released frorn tho arsenal List eveiiing, carne to lbo city on : Steamer?, fe&riug to trust themsclvei aiuong the Ucrinnns of the lowcr Ward, even under csoort. A!l coniplain bitterly of bad treatiuent during their confinemeut in tha nrsonal. Gcu. Frost and his officers gave tfaeir pnrole under protest, and the niño wero allowed to do the ! sumo when taldng oath not to bear arms ; agaiust tho United States. Heavy rains have fallen all doy, not withstaudiog whioh thu streets have becu i thronged by oxcited peoplo, a larre prol portion of whom loudly censure those in authoritv, for putting loaded arias into the hands of inexpericnced volunteers, to shoot down inotloDsive citizens for insuffi eient causes. All good citizens depreaate the action of lawlcss partios, and justly blame the troops for indisuriminate i tiring into crowds, aud cry out against : t lie unneccssary maruhing of aruied sol, diera tbrongh the city. In order to allay excitement and re store coiifulence to the people, Gen, Jlarnev ii-sucd a proclamation to the people of St. Louis and the State of Missouri, whioh has been posted throughout the city, exprossing docp regrct at tho state of thiugs existing here, pledging liimsclf to do all in liia power to preserve tho peace, and calling on the people Mrd tho public autliorities to aid liim in tho discharge of his duties. 11 o says tho military bree ander his oonamaad will ouly be used in the last extremity, and hopes he will not be compollcd to resort to martial law, but emphatically states that the public pcace must be preserved. and the livcs and property of the pfople protector]. He says that ho has not authority to ehange the loeation of the Home (iuards quartercd in the city, but to avoid all cause of irritation and excitement, if callod upon to aid tho local authoritieg he will use tho regalar anny iu prcfcroncc. In accordancc with tliis proelama'.ion, a battalion of regulars has been seut iuto tbe city and placed under the direction of the Poüoe ers, to at:t as a military polioo corpa. Considerable lawlesáncss has prevailed ! tbr the past two days. Several innocent Gennn'.is nave been shot on the Btreotfl I where the feeling againt the Germana is most intense, the regular voluntoers and Home Guarda being composed mainly of that class of citizcus, and it is through thoir acts so matiy innocent people have boon killed. Soveral persons cliarged with firiog on tho troops and shootiug ou the streets havo been arrested, and the pólice are constantly on the alert. Nows ot' the surrender of Camp Jacksou created intense excitement at Jefferson City, and Harris' military bill passed both House and Sonate in 15 minutes - Another commotion was created on the reception of a dispatch stathig that a largo forco of volunteers had left this city for Jeflferson. The powder recently purchased hore was iinmediately sent into tho country, and the State Treasury moved to a pLace of secunty. A large number of citizer.s enrolled themselves M Ilomo Guavd, aud several companiea öf troops aro expected from the surrounding counties in obedienco to a special cali of the Govornor. A session of the Legislatura was called after midnight, aud a bilí passed both Houscs extending the power over the pólice coinmissioners.and giviug the Governor auiple means for suppressing riots and in suivcctionary movemeuts throughout tho State. About a thousatid Illinois volunteers are stationed at Caseyville, seven ïnilep,' east of here. St. Louis, Mav i4_ Gen. Karney publishes thk tnorning an a-idress to the people of Missouri, in which ho calis atterA'ion to tho military bill recently p".sejd by the Legislatura, which he regardsas an indirect secession onün:'.oce, manifestl.y uncon slitutional, aód ought notto beuphcld by the good people of Missouri. He suys : ' Whatever rnay be the tenniQatiun of the present condition ol things iu respect to the cotton Stntcs, j Missouri mustjshare the destiny of the j Union. All her material interestspoint to this result, and so important is this iu regard to the great interest of tbo country, that I venturo the opinión that tbe whole power of the United States Government, if necessary, wil] be'exerted to maintain Missouri in the Union.'' Speaking of Camp Jackson, be eays the ñames oí Davis and iBeaurügard marked its main avenues; that a body of men organized in the interest of the secesssionists, bave been received there openly, bearing the dress acd badge distinguishing the army of tho so called Southern Confuderacy ; and leaves the poople to draw their own inferences, of tho character and ultímate purpose of the encamprnent. He ststes, bowever, there wore many goocl and loyal men in the camp, who were in no marnier responsible lor its treasouablu cbaractur. In conclusión, he says, " disclaimi ng all desire br inlention to intciiere with tho prerogatives of the State of Missouri, or wiih tha functions of ita executive, yet I regard it my duty, to oxpress to the peoplo in respectful but decided language, tb at vvithin the field and scope of rny command, the suprerne law of the bind must and shall ba raai'.:taincr!, and no subterfuges whatever, -wheÜ:er in iorm uf legislative acts or othervrise, pan lie penniUed to harrass or oppress the gcod iS abiding people of Missouri. I sha!! ezart my authority to profeet their persons and property irom viola tion of every kind, and shall deern it my duty to suppress all unlavvjul combinations oí mei), whether formed under a military organizutiou or otherwise."