The Millitary Importance Of Petersburg

[From the New York Times ] This exposition, while showing that we hoid 110 such relations to Peters, burg and i te comrnunicalions as to claim its berag tin. er siege, yet brings nat clearly tbe commuflding military im. portanceof this point with referente tö any operatiur.s against Eichmond by this line. Petersburg is, in faet, the key to Riehmo&d; and tho elabórate constntetion of ts deiences furnUhea standard of the high vahie set upnn it by the rebel military engineers. Viewed from a milii ry point 01 v?ew, it forms a poweríully fonified tete dr-point, cov. enng the p:;si-age of the rrver and the main lino of eommuiiicutious Irt Richmond southwavd. lts relations with that capital arc, lact, almost identical with those held by Bultiroore towardö AVashington mil ero the rebels in possession of the forraer point they ivould not menace our capital mere tban we would Ricb. mond, vvera -e once in possession of Petersburg. In fact, not is mueh- for even weve Iialtimore in the hands of the rebels, Washington would stil] have its water commiinrcatïoni, while Richmond is isolated from it. The rebel defensiva line was drawn around the city at a distanco of abut two miles from it, and formed a set oí de. tached redoubts after what is known as the " (ierman system." Of these works, there were seventeen, mounting from sis to eight uas eac.h.. Pbëy were beautiftd vn èmiat and powerful in constriu-lron, equal to the fortification oround Washington and connected by an infa-ntry parapet' the (ftrongest I have yet seeninnj experinnce over all parts of tha theater of vra. That they were left as fnadeqnately defeaded as they were, thereíore, can can onty be accounted for od tb hypothesis, whjch, indeed, ia no hfiget a hypothesis, but an ascertained fact- that GenèraJ Grant's manoenvTes d. ceived Lee, whose army was stiïl a clay's rriarcü oñ wïie.i this line of éefenses feil into our hands. Ihe rapidrty with which Beauregard was hurriw! forward to the defenses of Petersburg, and the tenaeity with whieh it has í-inei been held, are the best evidences of the kind of re.Mstance we should have met bad not General Grant been befbrchand with Lee. I have adverted to the nature of Ben, regard's defense of Petersburg. This has been a nwtter of lemark with the ablest hands of the army, it rivals bis defense of Charleston, and stamps hira as one of thu most skillful soldier in the rebel arrny. And certainly this estimate w not weakened, but, oñ iho contrury, heightened by a fact wtiioh astODishes every one hero. It is this: the Army of the Potomu has doí jet fret in front of Petersburg a single man belonging to Lee'.s army proper- Dot a man of the three corps of Longstreet, Eweil of Hill. Theforce defei.ëing Petersburg consists exehisively of tbe anny ol Beauregard, with sueh accensión outside of the ariay of fiorthern Virginia as he may have received. To thu natural query as lo wbere Lee's army i, I cun speak wkb no fullness of assuranee. There may be a corps in front of Butler, and it is veil known that fïve days ago, Ewell's corps was sent after Ilunter. The otlier corps is probably preparing anotber deiensivè line, in case Petersburg should fail. And this is the most unfavorable eontsequenee of the uubappy failureto take Petersburg; it gives the rebels time to forin their plans, niake their disposition, and enter on espeditious of the nature of diversión?, while the integrity of their railroad cominuuications aüows ihein the opportunity of receiving reinfercements. I liave endeavored in this reviev of the fituatioii to set it down freely aBll fuirly as it stands. If it is not precisely as encouraging as it rnight have been hoped, I shall have miseonveyed my own impressions if itis taken tobe discouraging. When Mrs. Graat left Washington for her Western home, she remainedi short time in New York, at the Fiftb hotel. Several gentleman called upon her, and in the oourse of the conversation congratulated her on the elevation of her husband, and expressed a hope that he would besuccessful in this campaign. Her whole inanner, quiet, dignified and reserved, seemed to expresi surprise that any one could doubt his success. Pausing a moment, she replied : " I have no doubt bul the General will succeed, for he was alwaye very obstinate man."