Wednesday, June 4, 2008

Military History and Warfare: The Thirty Years War: The military reforms of Gustavus Adolphus

By 1630 the Thirty Years War was in its twelfth year. Fearful of the creeping Habsburg encroachment into the Baltic, King Gustavus Adolphus of Sweden landed a small Swedish army of thirteen thousand men on the shores of Germany. For the next eighteen years, Swedish forces would play a key role in maintaining the Protestant cause. They were fortunate to be led by a man that would come to be known as the father of modern warfare.

Gustavus Adolphus

Gustavus Adolphus ascended to the throne of Sweden in 1611. In an age of religious extremism, he grew into a powerful advocate of the Protestant cause. As a child he had been well-tutored in military classics, as well as the works of Caesar and Vegetius. Crucially, he understood the organisational reforms introduced by Maurice of Nassau into the Dutch army early in the seventeenth century. Unlike many other rulers of the age, Gustavus had a firsthand understanding of the battlefield and of weapons. Early campaigns against the Poles and Russians in the 1620s gave him invaluable military experience. When he succeeded to the throne, Swedish forces were understrength, poorly organised and generally unprofessional. His reforms turned Sweden and the Swedish army into a first rate force that would later help determine the future of Europe.

Creation of a national army

In the early seventeenth century, most armies were heterogeneous compositions of various mercenary groups of different nationalities and ethnic groups. Maurice of Nassau had been one of the first to recognise that a truly professional army needed to be homogeneous. Gustavus decided to create an army that would remain Swedish at its core, but retain mercenaries in order to supplement numbers. To ensure that the mercenaries would be of high quality, he tried to retain forces that already had a proven track record of success. One of the best infantry regiments in the Swedish army was the Green Brigade, made up almost entirely of Scots.

To create the national army, he regulated the conscription process which had been gradually introduced in Sweden during the previous half-century. Drafts to supply men to the army were taken from existing militia units. He also made gifts of land for soldiers who had served for twenty years and set up administrative systems to ensure they were paid regularly whilst on active service. In order to support these military reforms, the king had to implement economic reforms at the same time. Gustavus expanded Swedish commerce, developing existing industries and natural resources. This allowed the state to operate on a regular annual budget and pay for its army.

Infantry tactics

Like Maurice of Nassau, Gustavus employed linear formations against the infantry tercios used by the Habsburg forces. He increased the number of musketeers and reduced the combat line to six ranks rather than the usual ten used by other armies. In addition, Swedish troops were equipped with the new, more reliable matchlock muskets. Gustavus also introduced packaged paper cartridges containing gunpowder and a ball. The system saved each musketeer considerable time in no longer having to worry about pouring the correct amount of powder under battlefield conditions.

The King’s reforms centred on working out effective tactics for attacking enemy infantry squares and heavy lines presenting a solid front of musket and pike. Swedish musketeers were trained to fire by volley of ranks so that continuous fire could be maintained. In preparing to receive an enemy charge, the musketeers formed up with the frontline kneeling so that they could fire a simultaneous volley. Once the enemy attack had been broken, pikeman and cavalry would advance.

Whilst pikeman were originally solely for defence (protecting the musketeers while they were reloading), Gustavus transformed them from being a purely defensive force into a means of offence. By removing most of their armour, pikeman were now able to charge across the battlefield. This aggressive use of the pike was innovative in an era where gunpowder was starting to dominate.

Reorganisation of cavalry

Gustavus made important contributions to the use of cavalry on the battlefield. His objective was to enable the cavalry to utilise its speed and impetus through a well-disciplined charge. Squadrons were eventually arrayed three ranks deep, fighting in the style of the Poles. Instead of merely harassing the enemy with pistol-fire, Swedish cavalry would now charge with swords at full speed. Only the first one or two ranks would fire their pistols, and only then before immediately attacking with their swords. Gustavus also equipped the dragoons with shorter versions of muskets, thus enabling them to fire from the saddle.


The King’s early experiences of war in the 1620s had given him valuable insights into the science of artillery. Gustavus understood that the expert use of artillery on the battlefield would enable him to pierce enemy lines, rather than simply bombard them. Therefore the calibre of guns in the Swedish artillery train were reduced to just three varieties, the 24-pounder, the 12-pounder and the 3-pounder. Each would have a specific role. Gustavus used the 3-pound guns as light field pieces for use directly as support for the infantry and cavalry units. Each infantry regiment was assigned two of these light guns. To make these guns more mobile, lighter gun carriages were employed along with shortened gun barrels and a reduction in the thickness of metal used in the artillery tubes. This resulted in fewer wagons and horses being required to pull the artillery. In 1625 the army’s 36-gun train needed over 1000 horses and 220 wagons. By 1630, the Swedish artillery-train of 80 guns required only 1000 horses and 100 wagons.

These changes required radical technological improvements in the areas of design, casting and metallurgy. Sweden’s vast natural mineral resources made the creation of a large artillery force a realistic possibility. Through experimentation and the employment of foreign experts, Sweden artillery became the finest in Europe. Accuracy was insisted upon and gunners were given regular practice. At the Battle of Breitenfeld in 1631, Swedish gunners were able to fire three shots to every one of the enemy.


Arguably King Gustavus Adolphus of Sweden was the first great modern military commander. His battlefield innovations were copied, but never bettered, by his opponents in the Thirty Years War. He took three distinctive units of the battlefield and moulded them into a force of combined arms. Arguable these tactics had not been seen in Europe since the Roman army. His contribution to military thinking and strategy dominated the age of gunpowder and pike and beyond.

Gary Dean Peterson, ‘The rise of an Empire in the sixteenth and seventeenth centuries: warrior Kings of Sweden’ (Jefferson, 2007)

Lars Ericson, Martin Hårdstet, Per Iko, Ingvar Sjöblom, Gunnar Asellius, Svenska Slagfält (Värname, 2004)

Philip J. Haythornwaite, ‘Invincible Generals’ (Poole, 1991)

Herman Lindqvist, ‘A History of Sweden’ (Värnamo, 2006)

Holger Herwig, Christian Archer, Timothy Travers, John Ferris, ‘Cassell’s World History of Warfare’ (London, 2003)

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