Valdemar III didn't abdicated as such. His uncle who ruled as Regent, was killed in his bed, in a very elaborate and successful medieval special forces operation, that ended up saving Denmark as a nation.
In fact the period 1332-1340 is known as the Kingless Time, because there was really no king in control of Denmark.
His uncle, Count Gert/Gerhard (he was German) was one of the richest men in Europe at the time.
By then most of Denmark had been pawned, Count Gerhard being the largest creditor.
As such all crown estates were now in the possession of mainly foreign creditors, who wanted to milk the cow as much as possible and were also in the process of introducing a feudal system, similar to what was in place in in central and western Europe.
But that didn't exist in Denmark for another 200 years. Here free men still had a voice and a vote in local councils - and they were ready (and often did) back up that right with the sword.
So Denmark being taken over and a new system imposed was not at all popular! As in no way! And that was something everybody, from old Danish nobility down to the poorest peasant could agree on.
There were rebellions, but they were defeated by foreign mercenaries. Equipped with the best and most modern equipment and well trained and battle hardened. And Count Gerhard was a very competent and experienced military leader. The Danes were militarily no match.
In the meantime Count Gerhard was setting himself up as de facto king of Denmark, through his nephew, because there was no way he would be elected king by the Danes - but that little detail could probably be corrected over time...
However, at the same time, a new Danish king had entered the scene, Christoffer II, who was king over Zealand and Southern Jutland. He came about because the Danes had elected Valdemar, not his uncle! Who apparently intended to be regent forever. I.e. de facto king of most of Denmark.
Unfortunately Christoffer II died and no new king was elected, so the political situation on the Danish side was muddied to put it mildly!
The young Valdemar wasn't happy with his uncle either, mind you. Wasn't it about time, he became king?
On top of that Count Gerhard had problems within his own family, where other members would also like a slice of the cake. In fact they'd like the whole cake!
Okay, rebellions didn't work, so what to do?
Assassinate Gerhard! But how? And who should do it?
In comes the squire Niels Ebbesen.
What follows now is a very compressed, simplified and incomplete account of a special forces operation. (Such "light" actions were actually very common in medieval times. Much more common than open combat, let alone major battles.)
By 1340 Count Gerhard toured his possessions in Denmark, going up through Jutland with a retinue and a considerable force of 4.000 men following up behind. Partly to ensure order and put pressure on other nobles. An "I am in charge, right?!?" operation.
At some point he came to the town of Randers were there was a castle. Here he would spend the night - safe behind thick walls.
Randers was a town alright, but of course small. The historical records mentions that the town had three "houses". In Danish that meant a large building made from stone, including a castle. But not a church or a cloister.
Niels Ebbesen with 47 men hid in one of these houses until darkness.
Then on the night of 1. April 1340 they sneaked inside the castle, found Count Gerhard's chamber and here Niels Ebbesen planted an axe in his head, as Count Gerhard sat up in his bed. Some of Count Gerhard's retinue was also killed in the melee.
After the killing, the Danes beat drums and announced the killing in order not to be seen as assassins and therefore dishonorable murderers. I.e. it was an open and therefore honorable killing.
Niels Ebbesen fled the castle, while the alarm was sounded and Count Gerhard's men grabbed their weapons and mounted their horses.
Niels Ebbesen fled across the only bridge over Randers Fjord. In the mean time other of his men, had loosened the planks on the bridge, so when Niels Ebbesen had passed, the planks were thrown into the fjord, making a pursuit impossible.
The Danes lost one man killed during the action.
What followed was remarkable. There was no revenge from Count Gerhard's family. An agreement was quietly made later on. In return for a fitting compensation, they would over time vacate the parts of Denmark that had been pawned to the family and Denmark again came under the control of a Danish King, Valdemar Atterdag, the formidable father to the even more formidable Queen Margrethe I.
That settlement was already being negotiated as early as 22nd April!
Niels Ebbesen was killed in battle on 2nd November. His corpse was dismembered and displayed, but it was taken by his men during the night at buried an unknown place.
That raises a number of questions:
Why would a mere squire undertake such a complicated operation?
Niels Ebbesen was not a squire in an English definition of the word, but more likely a sergeant. I.e. in medieval context an experienced junior officer. He belonged to the lower nobility and had an estate not far from Randers, so he knew the area well as well as knowing a lot of the locals.
It was quite common by this time that lower nobility opted out of becoming knighted. Either because they couldn't afford it, or just as likely because they had the professional soldier's contempt for "dandy amateurs" i.e. knights.
He would likely have served in the Baltic and/or with the Teutonic Knights in Northern Poland, where raids were extremely common, and gained experience there.
And having a "mere squire" carrying out the operation, would be preferable no doubt, for those who wanted Count Gerhard very dead. Especially if the operation went wrong.
Why would he undertake such an operation?
By all account he was loyal to the future King Valdemar Atterdag. He was no doubt also fed up with the taxation and with the very heavy handed approach by the mercenaries. Nor was he likely to be happy about losing his seat and vote in the local council.
How did he and his 47 men enter the town of Randers and stay hidden there, under the noses of Count Gerhard's men?
Someone, many in fact, helped him. Someone high up, mind you. Because a house made of stone was owned by one of the highest ranking citizens in the town.
Many would have turned a blind eye, especially to a local man like Niels Ebbesen.
How on earth did he manage to enter a no doubt well guarded castle in the middle of the night and locate Count Gerhard's chamber?
Randers and the castle would have crawled with sympathizers! There are ways in and out of any castle and with a good guide they could enter unnoticed. Count Gerhard would no doubt have been lodged in the best room and as Niels Ebbesen had probably visited the castle before, he could easily find it, so it was a matter of killing a few guards and a few pages, before they could enter Count Gerhard's room and kill him.
Getting away in the confusion wasn't that big a problem. Again someone had arranged for horses to be ready. 48 horses isn't something standing on every street corner, so that was well organized as well.
Why wasn't the bridge guarded? It may very well have been. But they were either sympathizers or killed.
Finally, who was behind all this? This after all require intelligence gathering, in order to know where Count Gerhard is at any given time and where he intends to go. Someone pretty high up supplied that information and passed it on quickly and securely.
Someone shielded and sheltered Niels Ebbesen and his men. After all 48 heavily armed men don't just ride happily along in the countryside unnoticed, not even back then.
Someone was ready to act swiftly upon the death of Count Gerhard negotiating a settlement only 21 days later. So that suggests that both sides was in contact behind the scenes.
It has never been ascertained who were the organizers behind the scenes.
Who wanted to kill Count Gerhard and who benefited from it?
The list is very long!
The future King Valdemar Atterdag.
"King" Valdemar III also wanted his uncle dead, so he could take over. he didn't though.
Count Gerhard's two sons, who had fallen out with their dad. They inherited a nice pile of money...
Other members of Count Gerhard's family who wanted their share. They ended up being outmaneuvered, even though not without a fight, one of which resulted in the death of Niles Ebbesen.
The majority of the Danes, including the nobility, especially in Jutland. For them it was return to peace and good old days of having a say in the local councils.
Why didn't Count Gerhard's family, especially his sons avenge his death?
Money. They got a lot of money, without having to risk their heads. After all this raid proved that anyone could risk waking up with an axe in the head! Literally.
It was an honest killing, so a fitting compensation would be acceptable.
And why fight endless civil wars and put down rebellions over and over again, risking your neck in the process? Not to mention that mercenaries are insanely expensive! Much better to pull out while there is still a lot of money in the money chests.
A very dramatic time.
And had Niels Ebbesen's raid failed, Count Gerhard may have had time to establish himself as the ruler over most of Denmark. With the result that today in 2021, in an alternative timeline, I might very well be sitting in a part of Bundesrepublik Deutchland typing this.