Friedrich I (German: Friedrich I; English: Frederick I; 1122-1190 June 10), nicknamed "Red Beard" or "Barbarossa" (Italian: Barbarossa; German: Rotbart), was the first Roman king of the Hohenstaufen dynasty and Holy Roman Emperor (reigned from June 8, 1155 to June 10, 1190). He was also a famous politician and military strategist in German history.
Frederick was born in 1122. His parents were Duke Frederick II of the House of Hohenstaufen and Judith of the Welf family in Bavaria. In 1147, he inherited the title of Duke of Swabian and became Frederick III. In 1152, he won the election for the German king and was crowned as the King of the Roman people of the Hohenstaufen dynasty. In 1155 (some say 1154), at the request of Pope Eugene III, Frederick went to Italy and received the Iron Crown in Pavia, where he was crowned as the King of Italy. In 1155, in St. Peter's Basilica in Rome, Pope Adrian IV conferred upon Frederick the title of Holy Roman Emperor, known as Frederick I. In 1178, Frederick was once again crowned in Arles, becoming the king of Burgundy.
Frederick I is considered one of the most successful rulers of medieval Germany, during which the Holy Roman Empire reached its peak in power and became the strongest country in Europe.

Frederick I's strong interest in Italy made Italian affairs the most important part of his life. In order to conquer the cities of Lombardy and make these rich regions a source of taxation for the empire, Frederick I carried out a long-term policy of invading Italy.
He has carried out 6 military invasions of Italy:
First time
In 1154, Pope Eugene III of Italy sent a letter of help to Frederick I. It turned out that there was a rebellion in Rome at that time, and the people rebelled under the leadership of a clergyman named Arnold. The rebels declared to abolish the Papal territory and allow the Pope to live an ordinary life. Frederick I did not give up the opportunity, sent troops to Italy, quickly suppressed the uprising, and convened representatives of various Italian city states to hold the Longcaria Conference, reaffirming Frederick I's absolute rule over Italy, from the appointment of officials to the collection of taxes, which could only be decided by the emperor;
Second time
In 1158, due to Frederick I's indulgence in soldiers plundering Italy, the northern Italian city states were completely angered. They formed a city-state group led by Milan and fought to the death against Frederick I. Frederick I, however, overwhelmed the rebels with powerful military violence, forcing the city-state alliance to surrender; [1]
But in the same year, the Milanese rebelled again and kidnapped the wife of Frederick I, Countess Beatrice I of Burgundy, in an attack, forcing her to ride a donkey out of the city. This is an insulting ritual of witnessing oneself paraded like a prisoner. This also led to Frederick's later retaliation.
Third time
In 1160, Frederick I invaded Italy again because the newly appointed Pope Alexander III could not tolerate the tyrannical red beard. He declared Frederick I's excommunication and supported the struggle of the city-state alliance. Frederick I then sent troops. After two years of fighting, Milan was captured, and the Milan representative surrendered wearing linen clothes and barefoot. However, Frederick I mercilessly drove the residents of Milan out of the city and dug trenches in the central square, rendering them barren. He also allowed the heads of prisoners to be cut off and used as balls to insult the people of Milan.

Fourth time
In 1167, Frederick I's massacre angered the Italian people, and Italian city states such as Venice and Verona formed a new Lombardy League, which quickly gained the support of the Pope. Frederick I once again sent troops, but at the beginning, he was unstoppable and captured Rome. Pope Alexander III fled. Later, the war reached a stalemate, and Frederick I's army was bravely resisted by the Italian people. In addition, a plague spread within the army, and thousands of brave veterans died. At this time, Frederick I had no choice but to withdraw his troops;
The fifth time
In 1174, due to his last defeat, Frederick I regrouped and marched out. At first, the Lombard Alliance wanted to negotiate, but Frederick I refused. Due to the increase in the number of cities in the Lombard League (22) and the increased experience of League soldiers, Frederick I's army failed in the Battle of Leniano near Milan, and Frederick I himself suffered serious injuries and had to surrender. In 1177, Frederick I signed the Treaty of Venice with Alexander III. Frederick I agreed to return the church property and no longer interfere in the internal affairs of the Pope. [2]
The sixth time
In 1183, Frederick I launched his final expedition to Italy, but it still ended in failure.
Frederick I signed the Treaty of Constance with the Lombard League, abolishing all resolutions of the Longcarian Conference, but allowing Frederick I to retain nominal powers of appointment and removal of personnel, and stipulating that the Lombard League would do a good job of reception when the emperor went on a tour.

Frederick I, like all talented emperors, attempted to control the rebellious princes within German territory. He issued a fiefdom decree in 1158, requiring all recipients of fiefdoms to serve in the military for the emperor. His other major initiative was to divide the large feudal territories into multiple pieces, thus separating Austria from the Duchy of Bavaria in 1156 and making it a duchy.

After his first expedition to Italy (1154), Frederick I had intended for Eugene III to crown him, but he did not expect Eugene III to pass away in anger. The newly appointed Pope Hadrian IV was very stubborn and rigid, constantly criticizing Frederick I's behavior and demeanor when he crowned him. Finally, he also asked Frederick I to follow the tradition of leading horses and supporting stirrups for the Pope.
Frederick I became angry and the coronation celebration suddenly turned into a slaughterhouse. Nearly a thousand priests fell under the army's butcher's knife, but Frederick I still received the title of "Holy Roman Empire" (ironically, after the failure of his fifth expedition to Italy, Frederick I knelt devoutly at the feet of Pope Alexander III to kiss the Pope's feet as a sign of "repentance").

Although Frederick I and his empire were renowned, his centralization policy still faced strong challenges in Germany, which had already formed feudal separatism. His main enemy and competitor was the Duke of Saxony, the Lion Henry, who also took over Bavaria in 1156.
In 1174, due to the lion Henry's refusal to participate in military action against Italy, Frederick I attacked Henry and defeated him. Most of Henry's land was taken away, only Brunswick and L ü neburg were preserved. But Frederick I did not include the confiscated territory of the lion Henry in the royal domain, but instead divided it among other dukes. From then on, it became a convention in Germany that confiscated duchy territories could only be owned by the emperor for a short period of time.

In 1189, after reconciling with the Pope, Frederick I, along with Lionheart King Richard I and Philip II Capet, led the Third Crusade to the East. However, he ultimately failed to reach the holy land.
The German army crossed the Balkans along the Danube River by land and arrived at Constantinople. Saladin bribed Byzantine Emperor Isaac Angelus to slow down the Crusades as much as possible. Isaac angered Frederick I, causing friction between the two sides and ultimately exchanging hostages. The two Roman emperors from both the East and the West also met before and after. The Shenluo army wintered in Edirne and crossed the strait to Asia Minor in the spring of 1190.
On May 18, 1190, the Shenluo army occupied Konya (Battle of Konya) through combat, and sometimes encountered harassment from scattered Arab light cavalry on the way. Apart from that, the Turks did not dare to launch a major attack on this army along the way. At the end of May, the army of the Holy Roman Empire entered Silesia, where the Armenians could safely travel to Syria.

However, on a scorching summer evening on June 10, 1190, the 68 year old emperor, while riding a horse across the Saleh River (also known as the Geksu River in medieval Latin), suffered a heart attack and drowned in extreme fatigue. His death was seen by Saladin as a manifestation of Allah, as he was the most powerful leader of this Crusade and also Saladin's most feared enemy.
Without the strong leadership of the emperor, the German army began to disintegrate. Some of them immediately went home, while the rest went to Antioch by boat or land. The Syrian troops suffered heavy losses due to small battles and scorching heat along the way, and Antioch was heavily hit by the epidemic. Only a small number of people participated in the siege of Ak, and when Friedrich's son, Duke of Swabia, passed away on January 20, 1191, this Holy Roman Crusader was completely dissolved. The leadership of the Third Crusade thus fell on the English and French.
There are different opinions about the death of Frederick I in later generations. Nicolo Machiavelli proposed in his book "A History of Florence" that the Red Beard died from bathing in the Saliva River, catching a cold, and falling ill; There is also a legend that Frederick was a great monarch who inherited the soul of Charlemagne in the 8th century and, like Charlie, received the Lance of Longinus stained with the blood of Jesus. Both of them also died due to the loss of the spear. Although the methods of death may vary slightly, they are equally regrettable.

"The great and peaceful messenger crowned by God, the glorious victor and the expanding empire, the Roman Emperor Frederick." - Frederick I's evaluation of himself in a proclamation released after his third expedition to Italy.
"The enemy forced you, and you never used your own strength to eliminate the shackles... So you summoned the Franks; it was like praying for no honor there." - Frederick I mocked the Romans.
"You must set an example for others, so that the shaken empire can recover through you." - Frederick I persuaded the lion Henry to join the expedition.
"Defender of justice, lover of the law" - contemporaries' evaluation of Frederick I.