With England in chaos in the English Civil War, and militarily weak even before that, it might have been thought that this would be a tempting target for foreign powers, either for invasion, or at least to determine the result. Yet this did not happen, at least on a significant scale. The obvious candidates historically would have been France and Spain, not least because Charles’s wife, Henrietta Maria, was a French princess. But both these countries were heavily involved in the Thirty Years War and internal revolts, and in no state for foreign adventures. Of course, this didn’t stop Parliament raising scares of invasion from Spain, France…. and Denmark.
Denmark was considerably larger at this time, being in a union with Norway, and was a significant military power. Crucially, it had withdrawn from the Thirty Years War in 1629 and so had uncommitted troops. Beyond this, there were personal links to the Royalist camp, not least of which was that Charles’s mother, Anne, had been the sister of the Danish king, Christian IV. Several prominent Royalists had even served with the Danish army, including Sir Jacob Astley, who commanded the Royalist infantry during the war.
Denmark was therefore an obvious place to ask for support, and Charles didn’t waste time, even in the Bishop’s wars against Scotland. And yet no troops arrived, even when he offered to mortgage Orkney and the Shetlands to Denmark. He tried again in 1642 to get troops for use against Parliament, even reportedly offering to add Newcastle to the mortgage deal, and again no troops were forthcoming.
Christian IV, wounded at the Battle of Colberer in the Torstensson War
Why no Danish troops?
Even a small Danish contingent would have been useful to Charles, especially at the start of the war when trained and experienced English infantry were in very short supply. Beyond this they would have been Protestant, avoiding some of the negative publicity arising from the Catholic Irish troops that he did get. So why did they not appear?
One reason was probably because Charles had offered a military expedition to support Christian back at the time of Denmark’s involvement in the Thirty Years war, and had not send any, so this hardly encouraged trust and fellow feeling. It has to be said that this was a bit of a pattern with Charles. And secondly, Parliament had made its own contacts with Denmark, that to an extent counter balanced Royalist influence. But the main reason was probably Sweden. Sweden was the major power in northern Europe at this time, and a bitter rival of Denmark. Christian could therefore hardly spare significant troop numbers for foreign adventures. And he was right, in 1643 Sweden launched a blitzkrieg, occupying much Danish territory and capturing a large part of the Danish fleet, the Torstensson War.
If the reported mortgage deal is real, it does raise some questions of what would have happened if it had been taken up. What exactly would the Danes have got in Newcastle, and how could they have enforced ownership if Charles had defaulted, as on past experience he probably would have done. Conversely, if the Danes had decided to keep the Orkneys, what then? Even worse, imagine that Denmark had passed on the mortgage to Sweden as war reparations, recovering the islands from the powerful Swedish fleet would not have been easy.
What Denmark did do
This is not to say that Denmark was no help to Charles at all. There were frequent complaints from Parliament of Danish arms shipments, at least one of which they managed to confiscate. Denmark also controlled the entrance to the Baltic, and to the major trading centre at Hamburg, via a fortress at Gluckstadt. In August 1643 Christian ordered all ships belonging to Parliamentary held ports found in Denmark, Norway or Gluckstadt to be seized and all imports from London to be banned.
So Denmark did have some influence on the English Civil War, but not as much as Charles originally hoped.
The English Civil War: Conflict and Contexts, 1640-49, edited by John Adamson.
The Impact of the English Civil War on the Economy of London, 1642-50, by Ben Coates