The attack on Marstrand was a successful Dano-Norwegian siege of the Swedish town of Marstrand and Carlsten fortress which took place between 21–27 July 1719 (N.S.) during the end of the Great Northern War.
After a Dano-Norwegian assault on northern Bohuslän, ships under the command of Peter Tordenskjold attacked the Swedes at Marstrand harbor and the immobile ships of the Swedish Gothenburg Fleet. The Danes subsequently attacked Carlsten fortress, whose garrison surrendered swiftly, partly because of psychological warfare.
The commander of the fortress, Colonel Henrich Danckwardt, was later sentenced to death by a Swedish court-martial for abandoning the fort while it was still deemed defensible.
The surrender of Carlsten fortress in 1719 is still surrounded by myths and legends.
Background After the death of Charles XII of Sweden on 11 December 1718 (N.S.) at Fredriksten fortress in Norway, the Swedish army marched back across the border to Sweden. The Great Northern War which had been fought continuously since 1700, had depleted fighting forces on both sides. As the Russian Pillage of Sweden posed a threat to Sweden's eastern seaboard, a large part of the Swedish Navy was operating in the Baltic Sea. Denmark-Norway, seeing this as an opportunity, put plans into motion to retake lost territories on the Swedish west coast. There were also plans for a naval and land invasion of Bohuslän.
The Swedish vessels which had previously been stationed in Gothenburg, the Gothenburg Squadron, had been attacked by Peter Tordenskjold's fleet in 1717 and had been ordered by Charles XII to remain scattered along the Bohuslän coast. A majority of the squadron was stationed in Marstrand by the Spring of 1719, and a few smaller ships were located near Strömstad. A couple of smaller vessels escorted transports between Gothenburg and Marstrand on the Nordre River, leaving a single galley to defend Gothenburg. The frigates at Marstrand were not operational, due to a lack of sailors and of food and equipment for the crews. Maintenance of the fortresses was handled poorly and in early 1719, local fortification experts complained over not getting paid for a long time. Similar concerns were raised by the naval officers' corps and the carpenters of Gothenburg.
Blockade and rearmament
At the time, Swedish privateers headquartered in Gothenburg were hijacking foreign vessels. This irritated Dano-Norwegian authorities, so on March 27, a Dano-Norwegian naval force, consisting of four ships of the line and a frigate, anchored in Rivö Bay outside of Gothenburg, blockading the city. The blockading force was under the command of Tordenskjold, who had recently been promoted to the lower admiral rank of schout-bij-nacht. To avoid endangering the peace conference that was to take place in Stockholm in the spring, Tordenskjold was ordered not to assault Gothenburg. In early June, the blockading naval force increased to seven ships of the line, two frigates, four barges, two floating batteries, one bombarderskip, five galleys and two Galliots. The smaller Danish vessels attempted to halt Swedish naval traffic between Nordre river and Marstrand. In mid-June, an additional 26 Danish merchant ships arrived from Øresund with supplies for the Danish blockading fleet.
The stockpiling of supplies in Strömstad in 1718 for Charles XII's army had resulted in the need for emptying the existing supply caches – which were filled to the brim – as quickly as possible. Many Swedish naval transports with cannons and supplies were moved to Sundsborg and Svinesund south towards Uddevalla. The removal of vital supplies caused the defense of northern Bohuslän to falter. By the end of May, a convoy of transport vessels had docked at Marstrand for transshipment to more capable vessels, where the cargo rerouted for further transport through Nordre river. A part of the convoy later returned to Strömstad. On May 23, Field Marshal Carl Gustav Rehnskiöld took command of Swedish troops in Bohuslän. Following an inspection in May, it was deemed that fortifications needed repair in several locations around the region.
The strong Danish blockade outside Gothenburg, with an estimated force of 1,300 soldiers and several special-purpose vessels for bombarding coastal defense positions, implied that the Danes were to attack either Marstrand or Älvsborg fortress. Captain Erik Sjöblad of the Gothenburg Squadron was ordered to moor all frigates and galleys to defend the harbor inlets. Rehnskiöld later gave the order to sink all anchored Swedish ships.
Assault on Strömstad
The peace talks in Stockholm failed, and King Frederick IV of Denmark ordered his troops to attack Sweden. Frederick IV had over 30,000 soldiers available in southern Norway, along with an attack force which would attack Strömstad from the north. A naval force with 8,000 soldiers was to invade Hisingen. The Swedish transport ships in Strömstad could not vacate Strömstad before Danish Vice Admiral Andreas Rosenpalm blockaded the only way out with a naval force of at least three frigates and four galleys at the end of June. After Rehnskiöld and the commander of the Gothenburg Squadron, Admiral Jonas Fredrik Örnfelt, had assessed the situation and had received intelligence that Norwegian forces were indeed marching towards Strömstad, the order was given to scuttle the transport fleet.
Several Swedish galleys and a smaller vessel attempted to slip out of the area at night through an inner channel but this route was blockaded as well. The Gothenburg squadron's galleys Kristiania, Lovisa and Bellona, along with the brig Pollux, were all sunk at Tånge Bay and Tångeflo south of Strömstad on July 5. The Strömstad and Gå På, equipped with 20 cannons each, were also sunk, along with fourteen fully loaded cargo ships in Strömstad harbor. All remaining caches were opened, so that both civilians and military could take what they could, and the remains were then destroyed. Afterwards, Swedish troops under the command of Rehnskiöld totalling around 5,000 – including the garrisons at the fortifications of Gothenburg, Nya Älvsborg and Carlsten – started south towards Uddevalla. The first Danish troops arrived in Strömstad between July 6 and July 8. Frederick IV later arrived along with additional soldiers.
By the end of June, heavy Danish surveillance of the Gothenburg archipelago had been arranged; a force consisting of eight vessels had been deployed between Klåver island and Tjuvkil. Since the vessels were attempting to halt naval traffic between Marstrand and Tjuvkil, and since they were pillaging the archipelago, the Swedes found it highly probable that Tordenskjold was planning to attack Marstrand. The Swedes performed a counter-attack against the Danish blockaders on the night of July 3, when the Swedish galley Lucretia and the brigantines Luren, Uppassaren and Framfuss from Kippholmen in the mouth of Nordre river, managed to creep down Hisingen and get past the Danish reconnaissance fleet without being spotted. The Danish galley Prins Kristian, armed with 9 cannons, was attacked and hijacked at Rivö's mouth.
Battle of Marstrand
Friday, July 10
In the first week of July, Tordenskjold scrambled an attack force which he planned to use in his assault on Marstrand. On July 10, the attack began. In the afternoon, the Carlsten fortress garrison reported seeing at least 18 Danish vessels. Tordenskjold had left ships of the line and frigates outside of Gothenburg and the attack force at Marstrand consisted partly of barges armed with cannons and mortars, and galleys with an additional 50 soldiers aboard each ship. Between 600 and 700 soldiers landed at Metsund on the east side of the undefended Koön, east of Marstrand. At the same time, 12 heavy mortars were being transported to the west side of the island. Only the far western part of the island could be bombarded from the fortress. Colonel Henrich Danckwardt, commander of Carlsten had on June 27 requested an additional 400–500 men, to prevent an invasion of Koön and Klåverön (south of Marstrand) but the soldiers had not arrived in time to repel Tordenskjold's attack. The Danish tactic of landing on the east side of Koön was virtually the same as the leading General of Norway, Ulrik Frederik Gyldenløve, had used when he occupied Marstrand and Carlsten at the Battle of Marstrand in July 1677.
Saturday, July 11
In the morning, heavy barrages were fired from the new Danish artillery stationed at Koön, at Carlsten fortress. Tordenskjold describes in one of his later writings of the new artillery station being heavily fired upon by three Swedish galleys, a barge and three other vessels. He also describes that the Danes were fired upon from Carlsten and its southern outworks. From 6–7 p.m., the cannon fire from Hedvigsholm outwork, which was placed on an island near Koön, consisted of four 36-pounder, two 12-pounder and two 6-pounder cannons. Hedvigsholm was only staffed with twelve men under the command of a non-commissioned officer. When the NCO realized that he would not be able to hold the fortress due to the heavy incoming fire, he sent word to Danckwardt about the situation. Squadron chief Sjöblad decided that the Hedvigsholm battery should be destroyed, to prevent the cannon falling into enemy hands. Danckwardt dispatched Lieutenant Breittenberg to destroy the cannon. Upon his arrival, Breittenberg found that both the Hedvigsholm garrison and the cannon were unharmed, but decided to carry on with his mission. When the Danes noticed that the battery fire from Hedvigsholm had ceased, they started firing upon the Swedish naval vessels in the harbor and managed to sink the vessel which was carrying the crew and ammunition of Hedvigsholm – around seven barrels of gunpowder – to the fortress.
After the events in Marstrand, a military hearing was held at the end of July 1719 with commander Danckwardt. Upon being asked why he had not ordered additional manpower to Hedvigsholm, which was considered the strongest and most effective battery to defend the town, which was also being supported by the galley Prins Fredrik av Hessen, Danckwardt defended his actions by arguing that if he had not destroyed Hedvigsholm, the outwork would have been captured, regardless of its number of personnel. He also pointed out that the enemy would have been able to wade between Koön and Hedvigsholm, something the hearing officials did not agree with.
Sunday, July 12
On Saturday night, another Danish cannon battery had been constructed, even closer to Carlsten and the northern river inlet. It was equipped with four 100-pounder mortars and between thirty and forty lighter mortars. Tordenskjold had also planned on using ten 24-pounder cannon but this was prevented by officers responsible for fortifications and the artillery. These officers had been brought on the ships but were not under Tordenskjolds command. They believed that the battery was unsafe, and refused to hand over the cannon. Fascines and other supplies necessary to produce the battery were not available, according to army officers. Tordenskjold then ordered a fahnenjunkers and nine gunners under his command, together with additional manpower from the ships, to build the battery. The heavy mortars were carried from the northern side of Koön to the new battery. When it was considered ready, Tordenskjold ordered a barrage against Carlsten, which had little effect on the fortress. Even though Tordenskjold had Swedish naval vessels in his firing range, he avoided firing against them in order to attempt to capture them unharmed.
Marstrand falls