Signal-flags in ancient military history, was a gilded shield hung out of the admiral’s gallery; it was sometimes a red garment or banner. During the elevation of this the fight continues, and by its depression or inclination towards the right or left, the rest of the ships were directed how to attack their enemies, or retreat from them.

Signals made by the colors of an army, (Signaux des enseignes, Fr.) The ancients had recourse to all the various methods which could be used by signals, to express the particular situation of affairs, and to indicate measures that should be adopted. If, during an engagement, victory seemed inclined more to one side than another, the colors belonging to the victorious party were instantly bent towards its yielding antagonist. This signal was conspicuous to the men, and excited them to fresh efforts. They imbibed the most lively hopes of success, and eagerly pressed forward to reap the advantages of bravery and good conduct.

When an army was hard pressed by its enemy, the colors of the former were raised high in the air, and were kept in a perpetual flutter and agitation, for the purpose of conveying to the soldiers, that the issue of the battle was still doubtful, and that nothing but courage and perseverance could determine the victory. If, in the heat of action, any particular regiment seemed to waver and give way, so as to cause an apprehension that it might finally be broken, its colors were instantly snatched out of the bearer’s hands by the general or commanding officer, and thrown into the thickest of the enemy. It frequently happened that the men who were upon the point of yielding ground and flying, received a fresh impulse from this act, rallied, and by a desperate effort of courage recovered the colors, and restored the day. This method of re-animating their legions was generally resorted to by the Romans. We have had instances in modern times, where the fortune of the day has been wholly decided by some sudden and unexpected act of an individual. In the reign of Louis XIV. a private soldier threw his hat into the midst of the enemy during a hard fought and doubtful battle, expressing thereby that fresh succours were arrived to strengthen the French army. This circumstance, so apparently trifling, produced the desired effect. It threw the enemy into confusion, gave the French fresh spirits, and finally determined the victory in their favor. We read of various instances in which signals have been used to express the personal danger of a king or general, who was fighting at the head of a select body of men. The knowlege of the critical position in which their leader stood, excited fresh courage in the rest of the troops, and drove them to acts of the greatest intrepidity. In the course of the present war some examples of the same sort might be adduced, both on the side of Austria, and on that of France. The bridge of Lodi, the passage of the Tagliamento, &c. would illustrate any observations we could make upon the subject.

Nor are the advantages which arise from the use of signals confined to these particular cases. Various circumstances grow out of the desultory nature of military operations, to render flags of communication indispensibly necessary. The vast scope which is given to modern tactics, makes it impossible that the human eye or voice should take in all the critical manœuvres or evolutions which occur, when an extended line is actually engaged. The right wing may be giving way while the left is gaining ground, and the centre might be in danger while the two flanks were rapidly advancing with apparent security against the enemy. Under these circumstances a general, by means of communicating signals, might be enabled to provide for every contingency, without losing time by sending his orders verbally. Although signal flags, in modern engagements, have been generally laid aside, their use has been acknowleged in the adoption of warlike instruments, which, by the variety of their sounds, convey the necessary directions to an engaging army.

The ancients had signals which they called mute signals, (signaux muets.) These consisted in certain actions or signs that were made by a general; such as waving the hand, brandishing a stick or sword, or by exhibiting to view any part of his dress, accoutrements, &c. Instances of the same kind have occurred among the moderns. Under this denomination may likewise be classed the different signals which are made for the movement, marching, and manœuvring of troops in and out of quarters. When troops are scattered or separated from one another, it is usual to communicate by means of fires lighted upon eminences during the night, and by smoke during the day.

In former times large pieces of wood were hung above the towers of cities or castles, which, by being drawn up or lowered, gave intelligence of what passed. This method has been succeeded by the invention of telegraphs, which answer every purpose of communication, when they can be established through an extent of country. At the battle of Fleurus, the French employed balloons, to which cords were attached, able officers elevated in the air sent down, by the cords, an account of the movements of the Austrians, a signal thus conveyed enabled Jourdan to direct a tremendous battalion fire, and a heavy charge of cavalry, by which the battle was decided. Besides those signals, there are others which may be called vocal and demi-vocal. The vocal signals are those of the human voice, which consist in the necessary precautions that are adopted to prevent a guard or post from being surprised, to enounce words of command in action, &c. Of the first description are paroles and countersigns, which are exchanged between those to whom they are intrusted, and which are frequently altered, during the day and night, to prevent the enemy from receiving any information by means of spies. The demi-vocal signals are conveyed by military instruments; the different soundings of which indicate, instantaneously, whether an army is to halt or to advance, whether troops are to continue in the pursuit of an enemy, or to retreat.

The demi-vocal signals, directed to be observed in the British service, as far as regards the manœuvring of corps, &c. consist of signals for the government of light infantry, and of cavalry regiments, squadrons, or troops: the latter are properly called soundings. Rifle or light infantry signals are to give notice—to advance; to retreat; to halt; to cease firing; to assemble, or call in all parties. Those signals should be always considered as fixed and determined ones, and are never to be changed. The bugle horn of each company should make himself perfect master of them. All signals are to be repeated; and all those signals which are made from the line or column, are to convey the intention of the commanding officer of the line to the officer commanding the light infantry, who will communicate them to the several companies or detachments either by word or signal.

Signal-staff. In matters of military parade it is usual to fix a flag, somewhat larger than a camp color, to point out the spot where the general or officer commanding takes his station in front or a line. This is called the signal staff.

SIGURGHAL, Ind. A feudal tenure.

SIGUETTE, Fr. The same as cavesson, a sort of noseband, sometimes made of iron, and sometimes of leather, or wood; sometimes flat, and sometimes hollow or twisted; which is put upon the nose of a horse, to forward the suppling and breaking of him.