April with the battle of Chancellorsville, it continued till the march to Mine Run in October--seven months; but considerable more than half the time was spent in camps at Falmouth, Warrenton, and Culpepper. The great campaign now in progress has consumed (at the time this article is written) three months, commencing after a six-months' interval of inaction, and already half the time has been spent in the trenches at Petersburg. Since so large a portion of the time of an army is passed in camps, that branch of military science which governs the arrangement of forces when stationary, is one of considerable importance. It is in camps that armies are educated, that all the details of organization are systematized, that the _morale_ of troops is cultivated, that a round of laborious though monotonous duties is performed. Nothing is so trying to the temper of the individuals composing an army as a long season in a stationary camp; nothing has more effect for good or for evil upon the army in the aggregate, than the mode in which the time, at such a season, is occupied. The commander who does not exercise care to have his camps pitched in the proper localities, to insure the observance of hygienic rules, and to keep his men employed sufficiently in military exercises, will have discontented, unhealthy, and indolent troops. The words 'camps' and 'cantonments' are frequently used in the newspapers without any discrimination; but they denote two entirely different methods of sheltering troops. A camp is defined to be the place where troops are established in tents, in huts, or in bivouac; while cantonments are inhabited places which troops occupy for shelter when not put in barracks. Of camps there are several kinds, according to the purposes to be effected by their establishment, such as the nightly camps while upon the march, camps of occupation, camps in line of battle, &c. Cantonments are most frequently used when, during the winter, or other considerable period of inactivity, it is necessary to distribute an army over a large district of country, so as to guard a number of points. We have not had any instance of cantonment, properly speaking, during the present war; but in Europe this method of disposing troops is frequently adopted.