The December Crisis is described as the only occasion when the Swedish king himself attempted to assert his power; previous attempts had always been staged by his queen, Louisa Ulrika of Prussia.

In 1767, French envoy Louis Auguste Le Tonnelier de Breteuil had suggested a coup to increase royal power to the Hovpartiet, a political group whose goal is the strengthening of royal power against the parliament of the Riksdag of the Estates.

In December 1768, the king refuses to sign state documents in protest to his limited power and on December 15, the king formally resigns his throne in order to bring about the gathering of a new Riksdag, during which a reform to increase his capacity could be introduced.

This creates a difficult political situation, as he had thereby technically abdicated and the nation is in interregnum.

The Hovpartiet suggests that the crisis could be used to stage a coup to establish absolute monarchy.

The queen, whose Coup of 1756 was a Hovpartiet project, opposes because she does not consider the time right for such a step and advocated negotiation with the Hats (party) and the Caps (party), but at this point, the Hovpartiet for the first time turns to the Crown Prince rather than the queen; however, the crisis cannot be used for a coup because the Caps party breaks an agreement.

On December 20, the government agrees to assemble the Riksdag and promises new reforms, and the king hereby agrees to retake the throne.

Thus the crisis is averted and the government can function again.

The Riksdag will however not be assembled until 1769, and it does not give the royal house more than an increased allowance.

Adolf Frederick, King of Sweden, is little more than a figurehead, the real power being lodged in the hands of the Riksdag of the Estates, often distracted by party strife.

Twice he endeavors to free himself from the tutelage of the estates.

The first occasion had been in 1756 when, stimulated by his imperious consort Louisa Ulrika of Prussia (sister of Frederick the Great), he had tried to regain a portion of the attenuated prerogative through the Coup of 1756, and nearly lost his throne in consequence.

On the second occasion during the December Crisis (1768), under the guidance of his eldest son, the crown prince Gustav, afterwards Gustav III of Sweden, he succeeds in overthrowing the "Cap" senate, but is unable to make any use of his victory.

French envoy to Sweden Louis Auguste Le Tonnelier de Breteuil had in 1767 suggested a coup to increase royal power to the Hovpartiet (English: The Royal Court Party), the name for a political group in Sweden during the age of liberty.

The Hovpartiet, in existence in one form or another since 1723, seeks to strengthen royal power against the parliament of the Riksdag of the Estates.

It is most known in history as the force behind Queen Louisa Ulrika's Coup of 1756.

During the early 1760s, Hovpartiet had allied with the Caps (party).

After the election of 1765, it had  allied with the defeated Hats (party).

At this point, it has only followers among the nobility in the Riksdag of the Estates.

During this time, it is led by Fredrik Carl Sinclair in parliament.

Queen Louisa Ulrika had lost her leading position within the party after 1766 in favor of crown prince Gustav.

In December 1768, the king refuses to sign state documents in protest to his limited power and on  December 15, the king formally resigns his throne in order to bring about the gathering of a new Riksdag, during which a reform to increase his capacity can be introduced.

This creates a difficult political situation, as he has hereby technically abdicated and the nation is in interregnum.

The Hovpartiet suggests that the crisis can be used to stage a coup to establish absolute monarchy.

The queen opposes because she does not consider the time right for such a step and advocated negotiation with the Hats  and the Caps, but at this point, the Hovpartiet for the first time turns to the Crown Prince rather than the queen; however, the crisis cannot be used for a coup because the Caps party breaks an agreement.

On December 20, the government agrees to assemble the Riksdag and promises new reforms, and the king thereby agrees to retake the throne: the crisis is hereby averted and the government can function again.

The Riksdag was however not assembled until 1769, and it did not give the royal house more than an increased allowance.

Gustav, the son of Swedish King Adolf Frederick, is in Paris, where he carries both the court and the city by storm, from February 4 to March 25, 1771.

The poets and the philosophers pay him enthusiastic homage, and distinguished women testify to his superlative merits.

With many of them he will maintain a lifelong correspondence.

His visit to the French capital is, however, no mere pleasure trip; it is also a political mission.

Confidential agents from the Swedish court had already prepared the way for him, and the Duke of Choiseul, the retired Chief Minister, resolves to discuss with him the best method of bringing about a revolution in France's ally, Sweden.

Before he departs, the French government undertakes to pay the outstanding subsidies to Sweden unconditionally, at the rate of one and a half million livres annually.

Count de Vergennes, one of the most prominent French diplomats, is transferred from Constantinople to Stockholm.

On his way home, Gustav pays a short visit to his uncle, Frederick the Great, at Potsdam.

Frederick bluntly informs his nephew that, in concert with Russia and Denmark, he has guaranteed the integrity of the existing Swedish constitution; he advises the young monarch to play the part of mediator and abstain from violence.

Gustav had first intervened actively in politics during the December Crisis (1768), when he compelled the dominant Cap faction, which mainly represents the interests of the peasantry and clergy, to summon an extraordinary diet from which he hoped for the reform of the constitution in way that would increase the power of the crown, but the victorious Hat party, which mainly represents the interests of the aristocracy and military establishment, refuses to redeem the pledges that they had given before the previous elections.  

Gustav has found greater success abroad.

Gustav III, on his return to Sweden, tries to mediate between the bitterly divided Hat and Cap parties.

On June 21, 1771, he opens his first Riksdag with a speech that arouses powerful emotions.

It is the first time in more than a century that a Swedish king addresses a Swedish Riksdag in its native tongue.

He stresses the need for all parties to sacrifice their animosities for the common good, and volunteers, as "the first citizen of a free people," to be the mediator between the contending factions.

A composition committee is actually formed, but it proves illusory from the first: the patriotism of neither Hat nor Cap faction is sufficient for the smallest act of self-denial.

The subsequent attempts of the dominant Caps to reduce him to a roi fainéant (a powerless king), encourages him to consider a coup d'état.

Sweden, under the sway of the Cap faction, seems in danger of falling prey to the political ambitions of Russia.

It appears on the point of being absorbed into the Northern Accord sought by the Russian vice-chancellor, Count Nikita Panin.

It seems to many that only a swift and sudden coup d'état can preserve Sweden's independence.

At this juncture Gustav III is approached by Jacob Magnus Sprengtporten, a Finnish nobleman, who has incurred the enmity of the Caps, with the prospect of a revolution.

He undertakes to seize the fortress of Sveaborg in Finland by a coup de main.

Once Finland is secured, he intends to embark for Sweden, join up with the king and his friends near Stockholm, and force the estates to accept a new constitution dictated by the king.

The plotters are reinforced by Johan Christopher Toll, another victim of Cap oppression.

Toll proposes to raise a second revolt in the province of Scania, and to secure the southern fortress of Kristianstad.

After some debate, it is agreed that Kristianstad should openly declare against the government a few days after the Finnish revolt had begun.

Duke Charles (Karl), the eldest of the king's brothers, will thereupon be forced to mobilize the garrisons of all the southern fortresses hastily, ostensibly to crush the revolt at Kristianstad, but on arriving in front of the fortress, he is to make common cause with the rebels and march upon the capital from the south while Sprengtporten attacks it simultaneously from the east.

The entire revolutionary enterprise is underwritten with loans procured from the French financier Nicolas Beaujon, arranged by the Swedish ambassador to France, Count Creutz.

Toll succeeds in winning the fortress of Kristianstad on August 6, 1772, by sheer bluff, and ...

Sprengtporten succeeds in surprising Sveaborg on August 16, but contrary winds prevents him from crossing to Stockholm.

Events will soon occur there that make his presence unnecessary in any case.

The Cap leader, Ture Rudbeck, arrives at Stockholm on August 16 with news of the insurrection in the south, and Gustav finds himself isolated in the midst of enemies.

Sprengtporten lies weather-bound in Finland, Toll is five hundred miles away, and the Hat leaders are in hiding.

Gustav hereupon resolves to strike the decisive blow without waiting for Sprengtporten's arrival.
He acts promptly.

On the evening of  August 18, all the officers whom he thinks he can trust receive secret instructions to assemble in the great square facing the arsenal on the following morning.

At ten o'clock on August 19, Gustav mounts his horse and rides to the arsenal.

On the way, his adherents join him in little groups, as if by accident, so that by the time he reaches his destination he had about two hundred officers in his suite.

After parade he reconducts them to the guard-room in the north western wing of the palace, where the Guard of Honor has its headquarters, and unfolds his plans to them.

Gustav now dictates a new oath of allegiance, and everyone signs it without hesitation.

It absolves them from their allegiance to the estates, and binds them solely to obey "their lawful king, Gustav III".

Meanwhile, the Privy Council and its president, Rudbeck, have been arrested and the fleet secured.

Gustav makes a tour of the city and is everywhere received by enthusiastic crowds, who hail him as a deliverer.

On the evening of August 20, heralds roam the streets proclaiming that the estates are to meet at the palace on the following day; every deputy absenting himself will be regarded as the enemy of his country and his king.

On  August 21, the king appears in full regalia.

Taking his seat on the throne, he delivers his famous philippic, viewed as one of the masterpieces of Swedish oratory, in which he reproaches the estates for their unpatriotic venality and license in the past.

A new constitution, the Instrument of Government, is read to the estates and unanimously accepted by them.

The diet is now dissolved.