He played an important role during the Thirty Years' War and was appointed Governor-General of occupied Prussia; he is also credited for having laid the foundations of the modern central administrative structure of the State, including the creation of counties (Swedish: län).

[4] One of Oxenstierna's more unusual intellectual qualifications was his knowledge of the Scots language, reflecting the importance of the Scottish expatriate community in Sweden at that time.

As Chancellor, he would regularly receive correspondence in Scots from his agent Sir James Spens, and he ventured into the language himself for an official letter to his Scottish counterpart, the Earl of Loudoun.

In return, the young king agreed to ensure the nobles further privileges and appoint Axel Oxenstierna Lord High Chancellor of Sweden.

For his efforts regarding these negotiations, Oxenstierna received the title of district judge in the hundred of Snävringe and, eventually, the barony of Kimito.

During the king's Russian and Polish wars he had the principal duty of supplying the armies and the fleets with everything necessary, including men and money.

The Polish-Swedish War was reinitiated in 1626, and on 7 October that year, Oxenstierna became Governor-General in the newly acquired Swedish possession of Prussia.

Prior to this, in September 1628, he arranged a joint occupation of Stralsund with Denmark to prevent that important fortress from falling into the hands of the Imperialists.

[8] When Sweden entered the Thirty Years' War in the summer of 1630, tolls from Oxenstierna-controlled Prussia, as well as food supplies acquired by Oxenstierna, were pivotal assets.

[1] He had also obtained credits from foreign businessmen, ensuring large sums of money making it possible to hire mercenary soldiers to the army used in Germany.

During the king's absence in Franconia and Bavaria in 1632 he held the appointment of legatus in the Rhineland, with plenipotentiary authority over all the German generals and princes in the Swedish service.

[9] This meant that Oxenstierna became supreme commander of the Swedish troops in Germany, although he let his subordinate generals be responsible for the military operations on a lower level.

[8] The, for the Swedish side, disastrous outcome at Nördlingen brought him, for an instant, to the verge of ruin and compelled him for the first time so far to depart from his policy of independence as to solicit direct assistance from France.

[1][7] His presence at home dominated all opposition, and such was the general confidence for Oxenstierna, that for the next nine years his voice, especially as regarding foreign affairs, remained omnipotent in the Privy Council.

[6] When the queen, a few years later, wanted to abdicate, Oxenstierna at first opposed this because he feared mischief to Sweden from the unruly and adventurous disposition of her preferred successor, Charles X Gustav.

His body was then moved to Jäder Church close to the Oxenstierna estate at Fiholm, in present-day Eskilstuna Municipality,[3] where a vault had been built in accordance with his wishes.

[8] In 1647, Wallonian merchant Louis De Geer, who had returned from a Swedish trading expedition to West Africa, gifted four enslaved Africans to Oxenstierna.

From 1612, when Oxenstierna was appointed Lord High Chancellor, until 1632, when King Gustavus Adolphus died, the two men struck a long and successful partnership.

[2] After the death of Gustavus Adolphus, Oxenstierna was the mind behind the Instrument of Government of 1634, in which, for example, the organization of the five Great Officers of the Realm was clarified.

His way of examining, reconsidering, testing, and sometimes rejecting his earlier opinions constitutes his legacy more than his ideas on particular points of policy.

[7] When he discovered that there were too few young noblemen to staff governmental positions, he worked to make it easier for boys outside the noble families to gain higher education, and gave them the possibility, eventually, to be raised to the nobility themselves.

The words were intended to encourage his son, a delegate to the negotiations that would lead to the Peace of Westphalia, who worried about his ability to hold his own amidst experienced and eminent statesmen and diplomats.

Oxenstierna has been portrayed on the stage and on the screen several times, mainly due to his role as mentor and guardian to the enigmatic Queen Christina.

He was played by Lewis Stone in Rouben Mamoulian's 1933 Hollywood movie Queen Christina, with Greta Garbo as the female lead role, by Cyril Cusack in Anthony Harvey's The Abdication (1974) and by Michael Nyqvist in Mika Kaurismäki's The Girl King (2015).

In August Strindberg's 1901 play Kristina, Oxenstierna is portrayed as a cold realist criticising Christina's extravagant lifestyle and her gifts to favourites.

[27] The bass part of Oxenstierna was first performed by Giovanni Carlo Casanova in Jacopo Foroni's 1849 opera Cristina, regina di Svezia.

Oxenstierna figures prominently in the Ring of Fire hypernovel by Eric Flint et al. until the fifth main sequence novel 1636: The Saxon Uprising in which he attempts to organize a counter-revolution to restore the supremacy of the aristocrats while Gustav II Adolf is incapacitated, but Gustav Adolf recovers and in chapter 52 Oxenstierna is properly rewarded for his treason, along with three of his staff officers who started to draw their guns.

The computer strategy game Europa Universalis IV has several in-game events related to Oxenstierna's reforms and regency.