Initial phase In May, the first movements of the war started as a Danish fleet under Jakob Brockenhuus sailed towards the Baltic. At
Bornholm, on 30 May 1563, the fleet fired on the Swedish navy under
Jakob Bagge, even though war had not officially been declared. A battle arose that ended with Danish defeat. German royal emissaries were sent to negotiate a peace, but at the meeting place of
Rostock no Swedes appeared. On 13 August 1563, war was declared by emissaries from Denmark and Lübeck in
Stockholm. The same month, Danish king
Frederik II attacked Älvsborg. At the beginning of the war the Danes advanced from
Halland with a 25,000-strong army of professional mercenaries and captured Sweden's gateway to the west,
Älvsborg Fortress, after only three days of bombardment and a six-hour assault on 4 September. This achieved the Danish aim of cutting off Sweden from the
North Sea, blocking the all-important
salt imports. Eric then attacked
Halmstad, without result; the Swedish counterattack was driven back by the professional Danish army. After the king's departure from his army,
Charles de Mornay stepped in as the commanding officer and was beaten by the Danish at the
Battle of Mared. At sea a battle broke out near
Öland on 11 September, whereafter the war took a pause.
Campaigns South in 1551
On 30 May 1564 a battle broke out between the Swedish navy and the Danish–Lübeck navy between
Gotland and
Öland. The Swedish navy was under the command of
Jakob Bagge, and the Danish–Lübeck navy was under the command of
Herluf Trolle. Bagge was captured and the largest warship of the Baltic, the
Mars (also known as the
Makalös), sunk. The Swedish navy retreated to Stockholm leaving a sea blockade in effect.
Klas Horn became the new commander and met the Danish fleet at the island Jungfrun north of Öland 14 August. An inconclusive fight left the sea blockade in effect. Horn attacked the provinces Halland and
Skåne in 1565 and made several attempts at
Bohuslän and
Uddevalla. The Danish burned old
Lödöse in the province of
Västergötland. Eric initially led the army against the Danish himself, but then turned over command to Nils Boije, who on 28 August 1564 took
Varberg. The Danish army under
Daniel Rantzau beat the Swedish army in the
Battle of Axtorna on 20 October 1565. The Swedes fared better at sea. Horn, commanding the Swedish navy, pursued a Danish–Lübeck fleet onto the German coast where most of it was destroyed. After this victory Horn steered for Öresund and levied a toll on passing ships. On 4 June 1565, the
Battle at Buchow took place on the Mecklenburg coast, in which the Danish–Lübeck commander Herluf Trolle was mortally wounded. In the
Battle of 7 July 1565, the Swedish navy under Horn defeated a Danish–Lübeck navy under Otto Rud near Bornholm, where Sweden captured the Danish flagship the
Jegermesther. Thus ensured the command of the eastern Baltic by the Swedes that year. In January 1566 Sweden unsuccessfully laid siege to
Bohus Fortress in
Bohuslän (then a Norwegian province). Daniel Rantzau then moved his forces into Västergötland. At sea Horn returned to taking toll charges in the Baltic. An indecisive battle at sea outside of Öland occurred on 26 July 1566. On 28 July, half the Danish–Lübeck Navy was lost in a storm at sea. Horn was then called to command troops on land, where he died 9 September.
North Sweden occupied the undefended Norwegian province of
Jemtland, which was quickly reconquered by a counterattack by forces under command of the Norwegian governor of
Trøndelag. The forces were unwilling to launch a counterattack on Swedish land. In 1564 the Swedes marched under Claude Collart and re-occupied Jemtland, as well as
Herjedalen and Trøndelag, including the city of
Trondheim. Initially facing little opposition from the locals, their subsequent ill treatment of the Trøndelag natives, along with tax pressure, laid the groundwork for later resistance to Swedish invasion. Sweden also launched attacks towards Eastern Norway. In the south-east Sweden captured
Båhus Fortress, but lost it in 1566. Another part of the army marched through the valley
Østerdalen in 1567, captured
Hamar, and continued towards
Oslo. and in the middle of February 1568 he returned to
Halland. Attempts were made to make peace between the fighting nations during these years. Negotiators included the dukes of
Pomerania, French messenger
Charles Dancay, and Holy Roman Emperors
Ferdinand I and
Maximilian II. The emperors wanted Denmark and Sweden to give back the territories won in
Livonia, during the ongoing
Livonian War, but Sweden refused to give in to those demands. In 1568, the Swedish duke
John staged a successful coup d'etat against his brother, King Eric. Enthroned as king with the name John III, he began negotiations with Denmark-Norway, and on 18 November the same year this led to a
draft peace agreement in Roskilde. This was turned down by the Swedes, however, and in 1569 war stirred again. The Danes attacked and reclaimed
Varberg, on 13 November. The Swedes on the other hand now had great success in
Skåne. == Peace negotiations and consequences ==