After the discovery of gunpowder, however, there was a gradual revival of scientific, or more properly methodical war, to which Gustavus Adolphus gave the first intellectual impulse. The conditions of warfare became completely changed by this great invention in ballistics. Fire-arms soon got into the hands of both infantry and cavalry. Artillery took on importance and effectiveness. Armies became numerically stronger, depots for the needful materials were established in their rear, and the troops were supplied from these depots. This gave great importance to fortifying cities and to fortresses, in which lay the provision and war material; and as rations, ammunition, and stores had to be constantly brought from these depots to the front,—to maintain the communications of the armies with these strong places became a matter of primary importance. For the loss of a great fortress containing the army’s bread and powder and ball might have as grave consequences as the loss of a battle,—even graver.
Armies, thus handicapped with heavier trains and with artillery-parks, had less mobility, and were less fitted for pursuit than the old troops, which could carry all they needed with them. Victories were not followed up. Battles became less decisive, and dropped into disuse. Strategy had not yet grown to be the science to which Gustavus Adolphus, Frederick, and Napoleon elevated it, and generals had not learned so to manœuvre as to make battles decisive when won. Modern war, up to the days of Gustavus, was clumsy and lacking in general scheme. It was rescued from this condition by the Swedish king.
In antiquity, battle was the head and front of all things, and armies were nimble and independent. In the seventeenth century, on the contrary, the construction and preservation of fortresses and depots, and communications with these, and operations against the enemy’s fortresses, depots, and communications became the chief study. This marked difference in system is shown in the military literature of these periods. Any operations which lay outside of battle, the ancients ascribed to the genius of the general, assumed that these were subject to no method and could not be learned; or at best classed them with mere stratagems. Their object and scope was not understood, nor indeed considered of much moment. Older military literature does not in any sense deal with them. Soldiers believed that the whole success of war was based on courage and hard knocks.
But about the time of the Thirty Years’ War, theorists had discovered that there were other means, besides battle, of doing harm to the enemy, and began to reduce such principles as they could extract from the campaigns of the better generals to a permanent form. Their work was, however, only partial and scrappy. The most important document which first saw the light was Frederick the Great’s “General Principles” or “Instructions” for his officers. This paper, written before the Seven Years’ War and purposely kept in manuscript for a number of years, was finally pirated and published in 1753. It is a noble work. But Frederick’s deeds inspired a yet more important one. Serving in the Austrian army as captain of light-horse, was a young Welshman of good education and extraordinary perceptions,—Henry Lloyd. This man’s inquiring mind was not satisfied with the half-and-half explanations which the then military books could give him of the wonderful exploits of the great king, whose marvellous manœuvres he had so often followed on scouting duty, and from which the Austrian army so bitterly suffered. He began, with singular critical and analytical equipoise, to study these and seek reasons for their success. He served under Ferdinand of Brunswick in the two last campaigns of the Seven Years’ War, and later was Major-general in the Russian army. He spent his old age in Belgium. Among other works he wrote a “Military and Political Memoir,” which contains the important part of his labors. It was issued in 1780. The ground-work of our modern science of war is therein laid down. It is the first work except Frederick’s in which are exhibited in comprehensible form the true principles of conducting war. It is here first pointed out that intellect and moral forces combined go to make up the great captain. But what Lloyd says is mainly applicable to his own times and conditions, and is not exhaustive. He remarks that the art of war is, like all other art, founded on well-settled rules, to which alterations can only be made in the application. He divides it into two parts, the material, which can be subjected to rules, and another part which one can neither limit nor teach, and which consists in the ability to apply the rules of the first part quickly and correctly under rapidly changing and various circumstances. This is the same distinction which Napoleon draws between what he aptly calls the terrestrial and the divine in the art. The divine part, says he, embraces all that comes from the moral forces of the character and talents, from the power to gauge your adversary, to infuse confidence and spirit into the soldier, who will be strong and victorious, feeble and beaten, according as he thinks he is. The terrestrial part comprises the arms, entrenchments, orders of battle, all which consists in the mere combination or use of everyday matters. It is singular that this analysis of the art of the great soldier is but one hundred years old, that only within three generations has been recognized its divine part.
The man, however, who has crowned with his acumen the written science of war is Jomini, who first became known as a young staff-officer of Marshal Ney’s, and died but twenty years ago. Though he rose to the highest rank in the Russian service, his career was as military adviser rather than as commander. His chief value to us lies in his having collated and so plainly set down the lessons taught by the great captains, particularly Frederick and Napoleon, that all may now study them, as during the last century they could not be studied,—were not even understood. He has enabled us to assimilate the history of war. Other military students have since written with equal profundity. But our debt to Jomini is not lessened thereby.
Gustavus Adolphus was born in Stockholm, in 1594, the son of Charles IX. of Sweden, but at a time when his cousin Sigismund III. occupied the throne. He was a lad of great personal beauty and strength, and his naturally bright mind profited well by the careful training he received. His boyhood showed all the traits of strong earnestness, clean-cut courage, and deep religious feeling which later characterized the Champion of the Reformation. Of naturally quick temper, in youth a blow followed a word; in manhood he acquired exceptional self-control. His education was largely under the direction of Oxenstiern, who later became his prime-minister, general, and greatest intimate. He was a constant reader, an eloquent and persuasive speaker, a poet whose religious verses are still sung in every household of Sweden. He was famous in athletics, and was both a noted rider and able swordsman.
The Swedish government was an elective-hereditary monarchy. Sigismund, a bigoted Catholic, was deposed when Gustavus was ten years old, and the lad’s father made king. Sigismund retired to Poland, of which country he was also monarch, and remained thereafter the sworn enemy of Charles and of Gustavus.
The young prince went through every step of military rank and training, and at seventeen was declared of age and participated with distinguished credit, and rare skill and enterprise, in a war with Denmark. In this same year (A.D. 1611) his father died, and, against all precedent, Gustavus Adolphus was chosen king. During his reign of twenty-one years, his people and he were an unit. The world has never seen a more striking instance of mutual love and confidence, justly earned, between king and people.
Sweden was at war with Denmark, Russia, and Poland. Gustavus determined to finish each war, if possible, singly and in turn. From the very beginning he showed in his military conduct that his intelligence ranged beyond the conventional method of conducting war, which he had been taught with so much care. In 1613 he conquered a peace with Denmark.
In 1614 he began war with Russia, making, meanwhile, a two years’ truce with Poland. In this year, and the next, he drew the attention of all Europe to his bold invasion of the Russian territory, at the point where now stands St. Petersburg, and was for the first time approached by the Protestants of Germany with a request to aid their cause. In 1617 Gustavus conquered a peace with Russia.