Why is Gustavus Adolphus of Sweden looked on so favorably in english-language writings of the 30 Years War?

Repost a previous answer

There is a problem in discussing such a prominent figure, "He is awesome because he is awesome, here are the ways he is awesome."

In terms of historiography, he did not appear as a major military figure until Michael Roberts' seminal work on The Military Revolution, published in 1955, which cites his own earlier work on Gustavus Adolphus and portrays his army as a major revolution in military tactics and organization. Since then, this view has both been challenged and expanded (see my profile page for many references). However, it was recognized that there was something special about Sweden's armies in the 30YW, even if it still debated exactly how unique its various aspects were.

In summary, Gustavus' reforms were one milestone among a general trend in the ongoing military revolution that had started in the 1500s; his victories in the 30YW should be put in proper context; however there is little doubt in the superior quality of the Swedish army he had landed with in 1630.

Below I explain two aspects: Was it a military revolution? Was it a battlefield revolution?

Was it a military revolution?

Roberts' Military Revolution work focused on infantry and cavalry innovations, in particular the increasing power of shot infantry and the rise of linear tactics, which Roberts credited first to the Maurice Reform in the Dutch army, and then to Gustav II Adolph; and the shock cavalry tactics rather than caracole. The latter further improved the Maurice organization by the aforementioned combined arms optimizations, what with artillery and cavalry.

Geoffrey Parker further argued in "The Military Revolution: Military Innovation and the Rise of the West, 1500-1800" that it was not only the infantry's increasing focus on firearms that enabled the military revolution in the early modern era, after all the Swedish were soundly defeated in Nordlingen in 1634 by a veteran, high-quality Spanish army ably led by the Spanish Cardinal-Infante Ferdinand and his cousin HRE Emperor Ferdinand, that was very much still organized and led in the "old Spanish way". Parker argued that it was the rise of professional army that led to the revolution, and this came about due to the appearance of trace italienne fortifications and the need (and ability) for states to fund large standing armies to fight the long sieges.

Going further, it was the Spanish who arguably led this development, what with their Army of Flanders and tercios of Italy. Finally, the Spanish army had also moved more and more towards firearms and away from pikes in organic fashion, which shows in numbers if not in tactical formations and operations. Many top commanders, starting with Alba in the 1560s and Spinola in the early 1600s, had asked for regulation for increasing the number of musketeers in infantry units. Further, the Spanish and Imperial formations had by then moved towards a linear formation, even if they were still centered around pike blocks, although operationally they were very distinct from the "pike blocks with muskets and arquebus in the many mangas or sleeves around the pike blocks" look of the 1560s.

Finally, when it comes to volley fire and moving toward linear formation, there is very good recent scholarship that show the Spanish and Imperials, along with everybody else, had themselves moved in this direction. Thus, it would not be accurate to attribute the novelty to the Dutch nor the Swedes. See for example, Fernando González de Léon's Doctors of the Military Discipline… in the Sixteenth Century Journal, 27 (1996), pp. 61-85; and also David Parrott's excellent The Business of War, 2012; F. Tallett and D. J. B. Trim's European Warfare: 1350-1750, 2010, goes a long way into debunking the myth that reiter or caracole cavalry were useless as is often claimed when Gustavus II Adolphus' reforms are discussed.

Was it a battlefield revolution?

Sweden's entry into the 30YW came at a crucial time when Imperial forces were busy sabotaging itself. In 1630 the Catholic-Imperial side had appeared completely winsome. Wallenstein and Tilly's forces reigned supreme, with no competing Protestant power in the conflict. Emperor Ferdinand II promulgated the Edict of Restitution, with the intention of recovering secularized Catholic fiefs back to the situation agreed on during the 1555 Peace of Augsburg. But internally, the situation wasn't exactly rosy, for Wallenstein had many critics, some jealous of his successes and some unhappy that in 1629 he made little significant engagement against the Protestants. Thus, in September 1630 the Emperor dismissed Wallenstein, who some observed to have expressed relief, for he knew his army was difficult to maintain, what with the limits of bureaucracy, logistics, and revenue.

Now, enter the Swedes ... except that they had to first be extricated off their engagement in Poland, using French and Danish money! Gustavus demanded that France pay him a large up front sum, and then 400,000 thalers annually.

Sweden benefited from confiscation of church properties as it became a Protestant power, a change from the top largely following Henry VIII's model, leading to significant increase in royal revenue. From here on, it was able to harness a system of soldiery that supplied the early manpower. Later on, it had to rely on a large number of mercenaries. Thus, it became completely dependent on French financial support in the 30YW.

To give you an idea, as they entered the 30YW in 1630, Sweden spent more than its revenue, yet still it didn't go enough to pay all these troops. The Baltic provinces were not able to further maintain such large armies of occupation, to quote Swedish reports they were "laid waste". Swedish setback in Magdeburg, leading to the city's sack in 1631, was blamed on the city's unwillingness to pay for Swedish troops to be mobilized. Gustav II Adolf's letters and declarations mention "fixed contributions, either to the expenses of war or troops, to be maintained at the charges of each members" as he refers to his intended alliance.

Finally, even following its victory at Breitenfeld, Sweden had to re-iterate its needs to France, explicitly stating that Sweden required from the King of France 400,000 Imperial thaler each year, which had to be paid on the continent, such that it was more convenient for payment of troops. All that led to Gustavus' march toward Lutzen, and his death there.

To that end the King of Sweden will take his share of the great burden of the war by bringing an army of 30,000 infantry and 6,000 cavalry at his own expense to Germany and maintaining it there. The King of France will contribute 400,000 Imperial thaler, that is, a million livres tournois, every year, which will be paid and accounted for without fail to the agents of the King of Sweden appointed for that purpose, either at Paris or Amsterdam, as the King of Sweden may find the more convenient; of which one half is to be paid on 15 May and the other on 15 November, each year.

Back to historiography

In the English language, Roberts was the most eminent scholar for a long time, thus the popular view came to be that Gustavus II Adolphus was the father of modern warfare. There was a telling lack of critical analysis and counter-argument, for a long time. The first major critique was by Geoffrey Parker, who published The Military Revolution -- A Myth? in 1976. It was then that English-language scholars started to pay attention to Spanish and Italian militaries. As far as whether pro-Protestant, anti-Catholic historiography contributed to this, it's hard to distinguish cause and effect, let alone whether this was done intentionally. As I wrote elsewhere, paraphrasing more recent English-language authors such as Wilson and Cranmer,

To many German historians dominated by Protestants -- the most prominent of which was Leopold van Ranke -- the goal was to shape a linear, continuous set of events defining a people that is based around nationalism and emancipation from foreign oppression. This meant that the narrative of continuity of the German Nation goes from the Battle of Teutonburgerwald in 9CE (when Germanic tribes defeated three Roman legions), the wars of the Reformation as Luther confronted the corrupt Catholic church, the Thirty Years' War that followed, and then the wars of liberation against Napoleon I of France. It is convenient then to link this to Napoleon III of France, and then to the rise of the new German state.

Pragmatically speaking, English-language scholars paid little attention to Spanish sources up until the second half of the 20th century, what with eminent scholars such as the great John H. Elliott paving the way. So it could be that scholars such as Roberts worked in the best way he could given what he had access to. See for example, other topics around leyenda negra, various myths around the Reformation, and the Spanish Inquisition.

And further, it is only now that we have many scholars with great range of expertise across different nations, eras, topics; such as Geoffrey Parker, Jeremy Black, David Parrott, et al.

All in all, I view all that as a sign of healthy scholarship, as long as historiography is delineated clearly. As in, how certain assertions were derived, how can we critically examine, etc. Rather than he is awesome because he is awesome.