In 1807, with Denmark under threat from Napoleon's forces, Brunswick took part in an expedition to prevent the Danish fleet falling into French hands.
Following the defeat of Prussia in December 1806, Denmark's continuing independence looked increasingly fragile.
It was feared that Denmark, under pressure from France, might deny Britain access to the Baltic Sea, something the British believed vital for trade as well as being a major source of the raw materials required for building and maintaining their warships.
Brunswick was one of 17 ships-of-the-line, together with 21 smaller vessels, sent to demand the surrender of the Danish fleet.
Under overall command of James Gambier, the British fleet left Great Yarmouth on 26 July.
On arrival off Gothenburg, on 1 August, Gambier despatched four ships-of-the-line and two frigates to guard the Great Belt and stop reinforcements being brought in from Holstein, where a Danish army of 24,000 was camped.
Brunswick remained with the main force.
Over the next twelve days more ships arrived, swelling the British force to 25 ships-of-the-line, 40 smaller warships, and 377 transports carrying 27,000 troops.

On 10 August, having refused initial demands by the British, the Danes made further preparations to defend their city – already heavily fortified with 174 guns of 24 and 36lb, and 25 of the largest calibre mortars available.
Additionally, and separate from the fleet moored in the harbour, a 64-gun blockship guarded the entrance with four 20-gun prames, two floating batteries and 25–30 gunboats.
There were 5,500 troops stationed in Copenhagen and around 3,000 sailors.
A contingent of 3,500 armed civilians also remained but the rest of the population was evacuated, while negotiations with the British continued.

Although no formal state of war existed at the time, on 13 August, a seventy-four and a sloop of war from Gambier's fleet pursued and, eventually, engaged and captured the Danish frigate, Frederickscoarn.
On 16 August the King of Denmark ordered that all British vessels should be seized and detained; and on 17 August, Danish gunboats left the harbour and set fire to an English merchant barque.
The British landed a contingent of troops 12 miles north of the city on 16 August, the fleet returning to Copenhagen later the following day, where Gambier issued a retaliatory proclamation that all Danish vessels were to be detained.
Brunswick was soon in accord through the capture of two enemy craft.
Further skirmishes occurred between 18–21 August while the British landed their remaining troops, invested the island with their ships and instituted a close blockade.
As the troops moved to lay siege to the city and construct batteries, they received heavy fire from Danish gunboats, which in turn were harassed by the smaller ships from the British fleet.

By 1 September, the French had arrived at Strasland and Gambier was obliged to send more of his ships to blockade the port and prevent the passage of reinforcements to Zealand.
Having now completed batteries for 48 mortars and howitzers plus twenty 24lb long guns, the commander of the British army, William Cathcart, and Gambier made a final appeal to the Danes, this time offering to return the ships at the end of hostilities.
An agreement could not be reached, however, and the following day the British opened fire on the city.
The bombardment continued, on and off, until 5 September, during which time much of the city had been destroyed.
The terms of the capitulation were ratified on 7 September and the British occupied the city while the ships of the Danish fleet were either removed or destroyed.
Of the prizes taken, 18 were ships-of-the-line, 10 were frigates and 14 were sloops-of-war, including Little Belt.
In addition, 25 gunboats were confiscated.
In 1807, with Denmark under threat from Napoleon's forces, Brunswick took part in an expedition to prevent the Danish fleet falling into French hands. Following the defeat of Prussia in December 1806, Denmark's continuing independence looked increasingly fragile. It was feared that Denmark, under pressure from France, might deny Britain access to the Baltic Sea, something the British believed vital for trade as well as being a major source of the raw materials required for building and maintaining their warships. Brunswick was one of 17 ships-of-the-line, together with 21 smaller vessels, sent to demand the surrender of the Danish fleet. Under overall command of James Gambier, the British fleet left Great Yarmouth on 26 July. On arrival off Gothenburg, on 1 August, Gambier despatched four ships-of-the-line and two frigates to guard the Great Belt and stop reinforcements being brought in from Holstein, where a Danish army of 24,000 was camped. Brunswick remained with the main force. Over the next twelve days more ships arrived, swelling the British force to 25 ships-of-the-line, 40 smaller warships, and 377 transports carrying 27,000 troops.
On 10 August, having refused initial demands by the British, the Danes made further preparations to defend their city – already heavily fortified with 174 guns of 24 and 36lb, and 25 of the largest calibre mortars available. Additionally, and separate from the fleet moored in the harbour, a 64-gun blockship guarded the entrance with four 20-gun prames, two floating batteries and 25–30 gunboats. There were 5,500 troops stationed in Copenhagen and around 3,000 sailors. A contingent of 3,500 armed civilians also remained but the rest of the population was evacuated, while negotiations with the British continued.
Although no formal state of war existed at the time, on 13 August, a seventy-four and a sloop of war from Gambier's fleet pursued and, eventually, engaged and captured the Danish frigate, Frederickscoarn. On 16 August the King of Denmark ordered that all British vessels should be seized and detained; and on 17 August, Danish gunboats left the harbour and set fire to an English merchant barque. The British landed a contingent of troops 12 miles north of the city on 16 August, the fleet returning to Copenhagen later the following day, where Gambier issued a retaliatory proclamation that all Danish vessels were to be detained. Brunswick was soon in accord through the capture of two enemy craft. Further skirmishes occurred between 18–21 August while the British landed their remaining troops, invested the island with their ships and instituted a close blockade. As the troops moved to lay siege to the city and construct batteries, they received heavy fire from Danish gunboats, which in turn were harassed by the smaller ships from the British fleet.
By 1 September, the French had arrived at Strasland and Gambier was obliged to send more of his ships to blockade the port and prevent the passage of reinforcements to Zealand. Having now completed batteries for 48 mortars and howitzers plus twenty 24lb long guns, the commander of the British army, William Cathcart, and Gambier made a final appeal to the Danes, this time offering to return the ships at the end of hostilities. An agreement could not be reached, however, and the following day the British opened fire on the city. The bombardment continued, on and off, until 5 September, during which time much of the city had been destroyed. The terms of the capitulation were ratified on 7 September and the British occupied the city while the ships of the Danish fleet were either removed or destroyed. Of the prizes taken, 18 were ships-of-the-line, 10 were frigates and 14 were sloops-of-war, including Little Belt. In addition, 25 gunboats were confiscated.
HMS Brunswick (1790)