_Troops of the line_ is a term applied only to such troops as form the principal line on the battle-field, viz:--The heavy infantry and heavy cavalry. These are technically called _infantry of the line_, and _cavalry of the line_. In this sense of the term, light infantry, light cavalry or dragoons, artillery, and engineers, are not classed as troops of the _line_. But this distinction is now pretty much fallen into disuse, and the division of an army into Staff and Administrative departments, and four arms of service--Infantry, Cavalry, Artillery, and Engineers--is now regarded as the most convenient, from being precise and definite in its meaning. The _general staff_ of an army includes all general officers of the army, and such officers of lower grades as are attached to this general duty, instead of serving with troops, or on special administrative duty. The general officers are--1st, the _generalissimo_, or commander-in -chief; 2d, _generals_, or marshals, as they are called in France, or field-marshals and generals of infantry and cavalry, as they are called in England and the northern states of Europe; 3d, _lieutenant-generals_; 4th, _generals of division_, or major-generals, as they are called in England; 5th, _generals of brigade_, or brigadier-generals, as they are sometimes called;--colonels, majors, captains, lieutenants, ensigns, and cornets or cadets, are also either attached to the staff, or form a part of the _staff corps_. The titles of "adjutant-general," and of "inspector-general," are given to staff officers selected for these special services, either in the general staff or in the several _corps d'armee_. No special rank is attached to these offices themselves, and the grade of those who hold them is fixed by some special rule, or by their general rank in the army. In the war of the Revolution, Washington held the rank of General, and in 1798 the rank of Lieutenant-general. In the war of 1812, the highest grade held by any of our officers was that of General of Division, or Major-general, as it was called. The highest grade in our army at the present time is called Major-general--a title that properly belongs, not to the general of an army, but to the chief of staff. Hamilton had this title when chief of Washington's staff; Berthier and Soult when chief of Napoleon's staff, the former till the close of the campaign of 1814, and the latter in the Waterloo campaign. General Jomini first greatly distinguished himself as chief of Ney's staff, and afterwards on the staff of the Emperor of Russia. Other generals have owed much of their success to the chiefs of their staff:--Pichegru to Regnier, Moreau to Dessoles, Kutusof to Toll, Barclay to Diebitsch, and Bluecher to Sharnharst and Gneisenau.