Gustav II Adolf (December 9, 1594 – November 16, 1632) was the 7th king of the Vassar dynasty of Sweden (reigned from October 30, 1611 to November 16, 1632) and the eldest son of King Carl IX. [36] An outstanding European military strategist and military reformer.
Gustav learned a lot from a young age and ascended the throne in 1611. He is only 17 years old. Faced with Sweden's internal and external difficulties at the time, he appointed Oxenselna as Prime Minister and successively implemented reforms in administrative, economic, military, and other areas, successfully strengthening Sweden's strength. In order to seek hegemony in the Baltic Sea, he first resisted Danish invasion in the Kalmar War, and then went to war with Russia and the Polish Lithuanian Commonwealth, ensuring Sweden's control over the eastern coast of the Baltic Sea. In order to weaken the Habsburg family of the Holy Roman Empire who believed in Catholicism, he led his army to land in Pomerania in 1630 and intervened in the Thirty Years' War in the German region. In the Battle of Brightenfeld in 1631 and the Battle of the River Leck in 1632, Gustav defeated the Catholic Union army one after another and caused the death of Count Tilly, the former general of the Holy Roman Empire, which gained fame in Europe. In November of the same year, Gustav unfortunately died in action during the Battle of L ü tzen with Wallenstein at the age of 38.
Gustav II vigorously promoted military reform. During his reign, he implemented a universal conscription system and established a strong standing army with strong combat capabilities; Simplify the military establishment, improve weapons and equipment, transform artillery into independent branches, and closely coordinate with infantry, cavalry, and logistics; Adopt flexible linear tactics. He is therefore known as the "father of modern (or modern) warfare in Europe" [2], and is also the only Swedish king to be granted the title of "Great Emperor" (Swedish: den store), while Puritans refer to him as the "Northern Lion" (German: Der L ö we aus Mitternacht) [3-4].

Early period
Gustav Adolf was born on December 9, 1594, at Tre Kronor Castle in Stockholm, the capital of the Kingdom of Sweden. He was the eldest son of King Carl IX of the Vassar dynasty (1550-1611604-1611) and his queen Christina of Holstein Gotop (1573-1625). [7-8]
Gustav received good education and strict training as the heir to the throne from a young age. His private teacher, John Schroder, was knowledgeable and had traveled extensively. He imparted various knowledge to Gustav, making him more talented than the average young man of his time. Gustav's formal courses mainly focus on Latin and theology, but he has a strong interest in rhetoric, debating, mathematics, geometry, political science, history, and literature. He can fluently speak Dutch, Latin, German, and Italian, and later learned a little English, Spanish, Polish, and Russian. He is familiar with European classical works and has been particularly dedicated to military studies. [8] His most admired hero in his mind was Maurice (1567-1625, 1585-1625), a renowned general who was then in power in Nassau, the Republic of the Netherlands. [1] [7]
Gustav accompanied his father from a young age to various places, even attending political meetings, participating in political and military activities. At the age of 13, Gustav took the oath of succession as his father at Uppsala Cathedral. At the age of 15, Gustav was responsible for managing the duchy located in Vastamaland, accumulating some experience in managing administration and finance. He also frequently talks with diplomatic envoys and gains many practical experiences as a ruler. [7] After Karl IX suffered a stroke, Gustav became a co ruler.

Carry out reforms vigorously
On October 30, 1611, Karl IX passed away and was succeeded by Gustav, who became Gustav II Adolf or Gustav II Adolph at the age of only 17. [1]
When Gustav ascended the throne, he faced a serious situation of internal and external difficulties, and he himself was also in a relatively fragile political position. [1] During the previous reign of the king, he devoted himself to promoting the feudal autocratic system, disregarding the role of the hierarchical council, and infringing on the rights and interests of the nobility. Moreover, their military activities and exploitation of the people aroused strong dissatisfaction from various social classes. Gustav's accession to the throne was in his prime and according to Swedish tradition, he could not directly govern. Some aristocrats took the opportunity to demand political participation, thereby exacerbating the political crisis. [1]
In order to stabilize the situation and get rid of internal and external troubles, Gustav made various concessions to the nobles. In his oath of succession, he pledged: without the consent of ministers and hierarchical councils, no laws will be enacted, no war will be declared, no peace will be made, no alliances with other countries will be formed, no additional taxes will be levied, no conscription will be imposed, and so on. He distributed a large amount of land to nobles who had made meritorious contributions in battle and appointed them to important positions. Subsequently, Gustav appointed the noble representative, Count Axel Oxsencherna, as the Chief Minister of the government. Later, Oxensherna became Gustav's capable assistant and close collaborator in handling domestic and foreign affairs. This series of concessions eased the discontent of the nobles and led them to support the king instead. [1]
In early 1617, Gustav was officially crowned. With the assistance of Oxensherna, he began to strengthen Sweden's strength, with the following main measures:
Continue to implement multiple administrative reforms of King Karl IX, strictly control the Swedish aristocracy, and support the business class to resist the aristocracy, concentrate government power, and streamline government institutions;
Strengthen the power of Lutheran missionaries and make them responsible for administrative tasks such as taxation;
Consolidate Sweden's school system, establish a new university, and inject vitality into another university.
Develop commercial plans to increase the output of exported goods and expand economic scale.
At the same time, Gustav encouraged foreigners, especially those from lowland countries, to immigrate to Sweden and invest. These economically savvy citizens established or revitalized many industries in Sweden. Sweden's copper and iron mines are being mined more efficiently, and its shipyards are producing more merchant ships and warships. The collection of tolls at Baltic ports obtained through war also brought income. These increases in income not only eased the burden imposed by the Danes, but also enabled Gustav to carry out costly military operations.

After the victory in the war against Russia, Gustav immediately began military reform. He implemented compulsory military service for the first time in Sweden, where men aged 15 to 44 were conscripted and formed a well-trained standing army of 36000 in Sweden. He replaced the bulky legion with smaller combat units; Universal use of firearms and establishment of flexible combat formations; Equip the military with advanced military technology, including arming artillery teams with lightweight fast guns; Improve the cavalry organization and establish a new supply system for military supplies; In actual combat, combine the preparation for the attack before the war with the resolute attack in actual combat. These reforms ensured Gustav's brilliant victory in the Thirty Years' War. [8]
Foreign War
While enhancing national strength, Gustav II was also committed to enhancing Sweden's status in Europe. He inherited the traditional policy of the Vassar dynasty to seize control of the Baltic Sea and engaged in continuous wars with neighboring countries. [8] Since Gustav, Sweden has entered the so-called Swedish Empire (Swedish: svenska stormaktsteden) period.
The Ruidan War
Main entry: Kalmar War
When Gustav ascended the throne, he first had to face the war between Sweden and Denmark. In May 1611, Danish King Christian IV (1577-16481588-1648), who dreamed of reconquering Sweden and restoring the Kalmar League, led his army to invade Sweden and quickly occupied the southeastern port of Kalmar (Kalmar Castle did not fall). Gustav, on the other hand, led soldiers recruited from East Yotland to capture Christianburg in Skarne (Scania), Denmark. In July, Karl IX was disadvantageous to the Danes in battle, and by August, Castle Kalmar and the island of Erland surrendered to the Danes one after another. However, before the death of Karl IX (early October), Gustav had already recaptured the island of Elan. [8] [30]
After inheriting his father's throne, Gustav intended to exchange his father's title as the "King of the Northern Laps" for Kalma, but was rejected by Christian IV. In 1612, Gustav launched a surprise attack on Scania. In May, Christian IV took advantage of the unstable political situation in Sweden and captured Elfsburg, then advanced towards the Stockholm Islands. Gustav tried his best to resist the invading Danish army and forced Christian IV, who had failed to besiege Stockholm, to return home. [1] [30]
Through mediation by Britain, Gustav was forced to reach the Treaty of Cornered with Christian IV on January 20, 1613, recognizing Denmark's occupation of Elfsburg and Gothenburg, and agreeing to pay Denmark 1 million taels within 6 years to redeem Elfsburg and Gothenburg, but Swedish ships were not required to pay tolls to the Danes. [1] Later, Gustav took advantage of Denmark's sinking into the quagmire of the Thirty Years War and sent troops to recapture Elfsburg.

Defeat Russia
Main entry: Treaty of Stolpovo
After blocking Denmark's offensive, Gustav shifted his focus to the east.
During the reign of Karl IX, Sweden intervened in the election of the Russian throne, occupied Novgorod, and forced the locals to recognize Gustav's brother Karl Philippe (1601-1622) as the Tsar. However, Gustav and his mother did not agree to let Karl Philippe go. [31]
In 1613, Tsar Mikhail Romanov (1596-1645, 1613-1645) of the Romanov dynasty was elected as the Shah Queen, and his situation in the Russian Swedish army became increasingly critical. In 1614, Gustav launched a war against Russia with the assistance of the Netherlands to prevent Russian forces from entering the Baltic region. In September, Gustav's military operation in Ingria (now near St. Petersburg, Russia) was largely successful, but his siege of Pskov suffered two defeats. Later, in preparation for participating in the Thirty Years War, Gustav agreed to negotiate with Russia. After a long period of negotiation, the two sides signed the Treaty of Stolpovo on February 27, 1617. [1] [8] [26] [31]
According to the treaty, Russia ceded the southwest of Karelia, Ingria, and Nottysburg, abandoned its claims against Estonia and Livonia, and paid a compensation of 20000 rubles. Sweden agreed to return Novgorod and other territories to Russia and recognize the throne of Mikhail. This treaty resulted in Russia losing its Baltic Sea outlet again, Sweden controlling the entire Gulf of Finland coast, and delaying Russia's rise as a major European power until the reign of Peter the Great. The treaty stipulates that merchants from both countries can engage in free trade in countries agreed upon by each other, but Swedish merchants are prohibited from traveling through Russia to Persia and the East, while Russian merchants are not allowed to travel through Sweden to Western European countries. [8] [26] [31]
After Gustav's triumph, he proudly declared to the Council of Ranks, "Without our permission, this enemy cannot go into the sea. The vast lakes of Ladoga and Chud, 30 miles of swamps, and several large fortresses are enough to keep Russia away from us. In the name of God, I hope Russia will not cross the minefield one step further."

Attack Poland
Main entry: Borui War, Battle of Walhoff
After only four months of peace with Russia, Gustav turned his attention to the south and restarted the war with the Eastern European powerhouse, the Polish Lithuanian Commonwealth. The two countries were hostile towards each other over the Baltic Sea region and evolved into a religious war between Catholic (Poland Lithuania) and Protestant (Sweden) countries. And the King of the Polish Lithuanian Commonwealth, Zigmund III Vasa (1566-16321587-1632), the cousin of Gustav, also long claimed to be the legitimate heir to the Swedish throne (Zigmund III also served as the King of Sweden from 1592 to 1599, but was later defeated and deposed by Gustav's father Karl IX). [1] [8]
Seeing Poland and Lithuania embroiled in a war with the Ottoman Empire, Gustav decided to take the initiative. [8] In 1621, the Swedish army captured the Polish port town of Riga in one fell swoop. Because the population here is mainly Protestant, he did not carry out any looting. In 1624, he occupied another Polish town and forced Lithuanians back from the coastal areas. In 1625, Gustav launched a military operation in Prussia, a vassal of Poland. [1]
On January 7, 1626, Gustav defeated Poland at a slight cost. Approximately 500 to 1500 Polish soldiers were injured or captured in the battle, while the Swedish army suffered minor casualties. In July, Gustav boarded Pilau in Prussia. Before intervening in the German situation, Gustav had already won the war against Poland and seized large areas of land along the Baltic Sea coast. [8]
On August 18, 1627, Gustav was seriously injured in the Battle of Techev. In September 1629, with the mediation of France, Sweden and Poland Lithuania reached the Treaty of Altmark. It allows Sweden to retain extremely favorable tariff revenue in the Prussian region. [9] [25]

Marching towards Germany
Main entry: Thirty Years of War
In the second phase of the Thirty Years War that shook Germany (1625-1629), Denmark, which fought against the Catholic Union, was defeated and withdrew from the war in 1629. The power of Holy Roman Emperor Ferdinand II (1578-1637, 1620-1637) of the Habsburg family expanded to the Baltic Sea, posing a serious threat to Sweden, which was attempting to establish a Baltic power. Gustav Adolf and his staff believed that Sweden was inevitably involved in European wars. They believed that in this situation, it was best to let the war take place as far away from Sweden's borders as possible. [9] At this time, French Prime Minister Richelieu (1585-1642) also made every effort to encourage Sweden to participate in the war. With Richelieu's mediation, Sweden and Poland Lithuania reached a ceasefire agreement in 1629, clearing the way for Sweden to send troops to Germany. [10] In January 1631, Sweden and France reached the Treaty of the Belwald Alliance, which stipulated that Gustav had an obligation to retain a force of 3000 infantry and 6000 cavalry in Germany, while France promised to provide support of 1 million livres per year. [9]
Sweden's motives for participating in the war can be roughly divided into three points:
1、 To prevent danger to his own country: Gustav was worried not only about the Baltic Sea plan in Habsburg, but also about the emperor cooperating with King Zigmund III Vasa of Poland and Lithuania to seize the Swedish throne;
2、 Expanding Sweden's Baltic territory by annexing parts of Germany;
3、 Protestants who liberated North Germany. [9]
In 1630, Gustav arranged for Prime Minister Orksenselna to lead 10000 troops to stationed in Prussia to deter Poland, Lithuania, and Russia. At the same time, he also arranged for thousands of troops and militia to stay in various key locations in Sweden, forming a second layer of anti invasion protection network and a reserve force for mobile support expeditionary forces. On May 20th, Gustav participated in the final national level conference. He held his 4-year-old daughter Christina and demanded that the representatives swear allegiance to her when he died in a foreign land. [24]
On June 24th, Gustav landed in Pomerania with 15000 people (or 12500 people). After landing, his most important task was to liberate the struggling German Protestant princes under imperial suppression and strive to form an alliance with them. When Gustav began to advance towards the north of Germany, he had only 4000 soldiers. But he quickly consolidated the influence of Protestants. On July 6th (also known as July 4th), Gustav led his troops to land on the island of Uzdolm at the mouth of the Oder River, invading the principalities east of the Elbe River, such as Brunswick, Mecklenburg, Brandenburg, and Saxony. Under a series of fierce offensives, Pomerania and Mecklenburg successively broke free from the control of the empire.

Famous in Europe
Gustav's invasion officially marked the beginning of the Swedish phase of the German Thirty Years War. But initially, except for princes such as William V of the Grand Duchy of Hesse Kassel (1602-1637) and Bernhard of the Grand Duchy of Saxony Weimar who were willing to follow, all other vassal states adopted a restrained wait-and-see attitude. [24]
At the beginning of the war, due to Ferdinand II's contempt, Gustav's military progress was quite smooth. When he began to form the Leipzig Alliance, Ferdinand II began to deploy heavy troops to the north and appointed the veteran Bavarian general John Zekras von Tilly (also known as Count Tilly) as the commander-in-chief. [24]
In a series of early confrontations, the Swiss army was invincible under the strict military laws of Gustav and was welcomed by the locals. The imperial army, on the other hand, indiscriminately burned and killed, earning the nickname "locust swarm". Especially with the massacre in Magdeburg on May 20, 1631, the German Protestant princes who had previously been wary of Gustav chose to ally with Sweden. The Electors of Brandenburg, Saxony, and the Duke of Mecklenburg all offered Gustav hostages, money, and troops, requesting protection. In early 1631, France began providing aid to Sweden, and Russia also sold Sweden food and other military supplies on the most favorable terms. After uniting the feudal lords in the north and receiving assistance, the Swiss army began to penetrate deep into the German hinterland in May 1631. [8]
In September 1631, Gustav commanded the Swedish army of about 47000 people (including about 19000 Saxon Allies), with about 80 guns, to confront the almost evenly matched Holy Roman Empire Tili army. He did not allocate troops evenly, but instead sandwiched 7 infantry regiments with musketeers, focusing on their right wing direction. After the battle began, both sides shelled each other. The Tili army launched an attack after shelling, but their cavalry's seven attacks were all repelled by the Swedish army's salvo fire from their smoothbore guns. Afterwards, the Tili army flanked back to the weak left flank of the Swedish army and launched an attack. Gustav urgently mobilized second line troops to support the left flank and intercepted head-on under the cover of artillery fire. Just as the Swedish army was engaged in fierce fighting on the left wing and the Saxon army was fleeing, Gustav quickly grabbed the fighter jet and ordered his right-wing troops to quickly attack the left wing of the Tili army, and personally led four cavalry regiments to charge towards the enemy. The Tilly army was defeated, with 12000 casualties and 7000 captured. All supplies and artillery were acquired by the Swedish army, while the Swedish army only suffered 3000 casualties (see Battle of Brightenfeld). [11] Tili himself was injured and fled south, causing shock in Europe. Gustav was given the nickname "Northern Lion". [8] This is the first time that linear tactics have been applied on the European battlefield.
The outcome of the Battle of Brightenfield completely shattered Ferdinand II's plan and shocked the emperor. [12] On the other hand, Gustav gained fame during World War I in Germany, and his prestige, honor, charm, and popularity due to strict military discipline earned him a status like a savior.

After Brightenfield's great victory, Gustav recaptured Mecklenburg and restored his original position as Duke. At the same time, a combat meeting was held, and it was decided to personally lead the army westward and arrange for the Saxons to advance southward. Gustav's westward advance requires a fragmented political structure. The political landscape of western Germany is the most complex in the German region, where there are both Protestant countries and Catholic princes. They are both interdependent and full of contradictions with each other. The complex political religious structure made it impossible for this imperial territory to form a unified force to resist Gustav, and it was only a matter of time before each was defeated.
At the same time, Count Tilly is regrouping and regaining his vitality. After retreating to the area around the Weser River, he recruited the imperial garrison in Lower Saxony and also met with two generals, Fugel and Altringer. Although he repeatedly requested that Bavarian Elector Maximilian I allow him to fight against Gustav again to wash away his shame, the heavy losses of Brightenfield made the Grand Duke timid and forced him to hold his ground, saving Gustav from any worries about conquering the Rhine region.
Before advancing into the Rhine River basin, Gustav took Leipzig and Erfurt. The arrival of Gustav caused mixed reactions among the lords. Hesse Kassel, Frankfurt and other cities surrendered, Mainz, Maria Berg and others resisted stubbornly, while the diocese of Uzbekistan and Bambeck appeared submissive. Anyway, Gustav strictly prohibits soldiers from committing violence and plunder, treats conquered enemies leniently, never forces the implementation of religious orders for unity, and also takes care of the dignity of local rulers. These mild policies contrast sharply with the harsh style under the emperor's rule. The capture of Mainz marked Gustav as the new owner of the Rhine River. Through the campaign in this area, he cleared Habsburg of its remaining troops and ruling forces, and Lower Saxony, Pfalz, Hesse, and Westphalia all joined the Swedish camp.

At the same time, international relations in the German region have undergone complex and profound changes. The core of the Catholic League, Bavaria, saw a large army under pressure and hoped to borrow France to put pressure on Gustav, making him hold Bavaria high. France is also willing to add an ally in the German region, which will help it manipulate the situation. Due to Gustav's advance into the Rhine River and the outer edge of France's eastern sphere of influence, King Louis XIII of France harbored resentment. Many feudal lords who were hostile to Sweden took the opportunity to send envoys to persuade the French king to stand with the emperor, but Richelieu made every effort to make France appear neutral and urged Bavaria to negotiate with Sweden to continue maintaining France's maximum interests in Germany. [24]
Gustav knew that Bavaria was the heart of the Catholic League. In the negotiations, he proposed that Bavaria could maintain neutrality and Sweden would not invade any inch, but the premise was that Bavaria would sever its alliance with the emperor and impose a series of very harsh conditions such as all aid, extensive disarmament, and no action to be taken in subsequent military actions. At the same time, a secret letter written by the Duke of Bavaria to General Babenheim was intercepted by Swedish cavalry, revealing Maximilian's true intentions. Negotiations were just a cover, and the Duke wanted to strengthen his defense deployment and recall Tilly. He had no intention of negotiating with Sweden. [32]
After the harsh negotiations with Bavaria broke down, Gustav invaded Bavaria in March 1632. Maximilian urgently recalled Count Tilly while deploying heavy troops along the Lech River. On March 9th, Tilly defeated the Swedish army led by Gustav Carlsonhorn (1592-1657) in the Battle of Bamberg, but Gustav occupied Nuremberg on March 31st. On April 15th, in the Battle of Ryan, Gustav led his army to successfully cross the Lech River, causing serious injuries to Tilly. Tilly retreated to Ingolstadt. On the 20th, Gustav occupied Augsburg. Later, they began to besiege Ingolstadt, during which Tilly Butler died (April 30th). In early May, Gustav abandoned the siege and turned deep into Bavaria. On May 17th, the Swiss army occupied Munich. This is the pinnacle of the Swedish phase of the Thirty Years War.