Wars of insurrection to gain or to regain liberty; as was the case with the Americans in 1776, and the modern Greeks in 1821.

Wars of independence from foreign dictation and control as the wars of Poland against Russia, of the Netherlands against Spain, of France against the several coalitions of the allied powers, of the Spanish Peninsula against France and of China and India against England.  The American war of 1812 partook largely of this character, and some judicious historians have denominated it the war of Independence, as distinguished from the war of the Revolution.

Wars of opinion, like those which the Vendeans have sustained in support of the Bourbons, and those France has sustained against the allies, as also those of propagandism, waged against the smaller European states by the republican hordes of the French Revolution.  To this class also belong—­

Religious wars, like those of Islamism, of the crusades, and of the Reformation.

Wars of conquest, like those of the Romans in Gaul, of the English in India, of the French in Egypt and Africa, and of the Russians in Circassia.

National wars, in which the great body of the people of a state engage, like those of the Swiss against Austria and the Duke of Burgundy, of the Catalans in 1712, of the Americans against England, of the Dutch against Phillip II., and of the Poles and Circassians against Russia.

Civil wars, where one portion of the state fights against the other, as the war of the Roses in England, of the league in France, of the Guelphs and Ghibelines in Italy, and of the factions in Mexico and South America.

It is not the present intention to enter into any discussion of these different kinds of war, but rather to consider the general subject, and to discuss such general principles and rules as may be applicable to all wars.

War in its most extensive sense may be regarded both as a science and an art.  It is a science so far as it investigates general principles and institutes an analysis of military operations; and an art when considered with reference to the practical rules for conducting campaigns, sieges, battles, &c.  So is engineering a science so far as it investigates the general principles of fortification, and also artillery, in analyzing the principles of gunnery; but both are arts when considered with reference to the practical rules for the construction, attack, and defence of forts, or for the use of cannon.

This distinction has not always been observed by writers on this subject, and some have asserted that strategy is the science, and tactics the art of war.  This is evidently mistaking the general distinction between science, which investigates principles, and art, which forms practical rules.

In popular language, however, it is usual to speak of the military art when we refer to the general subject of war, and of the military sciences when we wish to call attention more particularly to the scientific principles upon which the art is founded.  We shall here consider the military art in this general sense, as including the entire subject of war.