By companies on the left backwards wheel. The left pivot man of each company faces at this cautionary word, and remains a fixed point, on which the rest wheel back when they receive directions so to do. When the column of companies is to be wheeled into line, the word on is equally understood to direct the moveable parts of each company towards the given pivot which faces, and remains a fixed point. In the British drill instructions, they say, to the left wheel into line; but in the third part of the regulations to is wholly omitted, and the commanding officer uses the term left wheel into line, and vice versa; the preposition on is here understood: for it is evident, that in breaking into column the component parts of a line wheel as much from a given point, as they do to a given one, when the column returns into line. Whereas by using on, or understanding it to be used, when, for the sake of abbreviation, it is omitted, we preserve the true meaning of the preposition, keep the men in the recollection of the necessary adhesion, and shew, that whether you wheel backwards or forwards, from line into column, or from column into line, there is one invariable fixed point on which you move. It is more proper to say, on the right or left forwards wheel into line, in lieu of to.
ONAGRA, (Onagre, Fr.) a warlike machine, which was used by the ancients to throw stones of different sizes. It is mentioned by Vegetius.
ONDECAGON, a figure of eleven sides and angles.
ONSET, assault, storm, attack.
OPEN, in military movements and dispositions is frequently used, but it is seldom applicable to any operations in face of an enemy; the ranks, &c. on such occasions being generally compact and close. In formation, the word open is opposed to close, viz. open column, open distance, open order. It also constitutes part of a word of command; as rear ranks take open order; in opposition to rear ranks take close order.
Open distances in column. (Distances entieres en colonne, Fr.) The intervals in these cases are always equal in depth to the extent in front of the different component parts of the column.
Open flank, in fortification, that part of the flank, which is covered by the orillon. See [Fortification].
OPENING of trenches, the first breaking of ground by the besiegers, in order to carry on their approaches towards the place.
OPERATIONS de guerre, Fr. See [Military Operations].
Military OPERATION. Military operations consist in the resolute application of preconcerted measures, in secrecy, dispatch, regular movements, occasional encampments, and desultory combats, or pitched battles.