Duke of Swabia in the context of "Frederick I, Holy Roman Emperor"

Frederick Barbarossa (December 1122 – 10 June 1190), also known as Frederick I (German: Friedrich I; Italian: Federico I), was the Holy Roman Emperor from 1155 until his death in 1190. He was elected King of Germany in Frankfurt on 4 March 1152 and crowned in Aachen on 9 March 1152. He was crowned King of Italy on 24 April 1155 in Pavia and emperor by Pope Adrian IV on 18 June 1155 in Rome. Two years later, the term sacrum ("holy") first appeared in a document in connection with his empire. He was later formally crowned King of Burgundy, at Arles on 30 June 1178. His nickname of Barbarossa (meaning "Red Beard" in Italian) "was first used by the Florentines only in 1298 to differentiate the emperor from his grandson, Frederick II ... and was never employed in medieval Germany" (the colour red was "also associated in the Middle Ages with malice and a hot temper"; in reality, Frederick's hair was "blond", although his beard was described by a contemporary as "reddish"). In German, he was known as Kaiser Rotbart, which in English means "Emperor Redbeard". The prevalence of the Italian nickname, even in later German usage, reflects the centrality of the Italian campaigns under his reign, and "remains to this day one of the [most] powerful historical monikers."

Frederick was by inheritance Duke of Swabia (1147–1152, as Frederick III) before his imperial election in 1152. He was the son of Duke Frederick II of the Hohenstaufen dynasty and Judith, daughter of Henry IX, Duke of Bavaria, from the rival House of Welf. Frederick, therefore, descended from the two leading families in Germany, making him an acceptable choice for the Empire's prince-electors. Frederick joined the Third Crusade and opted to travel overland to the Holy Land. In 1190, Frederick drowned attempting to cross the Saleph River, leading to most of his army abandoning the Crusade before reaching Acre.

The Upper Rhenish Circle (German: Oberrheinischer Reichskreis) was an imperial circle of the Holy Roman Empire established in 1500 on the territory of the former Duchy of Upper Lorraine and large parts of Rhenish Franconia including the Swabian Alsace region and the Burgundian duchy of Savoy. Many of the circle's states west of the Rhine river were annexed by France under King Louis XIV during the 17th century, sealed by the 1678/79 Treaties of Nijmegen.

Frederick II (German: Friedrich II, 1090 – 6 April 1147), called the One-Eyed (der Einäugige), was Duke of Swabia from 1105 until his death, the second from the Hohenstaufen dynasty. His younger brother Conrad was elected King of the Romans in 1138.

Mainz-Kostheim (German pronunciation: [ˈmaɪnts ˈkɔsthaɪm]) is a district administered by the city of Wiesbaden, Germany. Its population is 14,381 (As of 2020). Mainz-Kostheim was formerly a district of the city of Mainz, until the public administration by the city of Wiesbaden was decided on 10 August 1945. The reason for this had been the easy control of the Allied Occupation Zones in Germany, where the Rhine formed the border between the American sector and the French sector. Mainz-Kostheim faces the city of Mainz on the opposite shore of the Rhine river.

In 1184 Frederick I, Holy Roman Emperor held one of the biggest diets of the Middle Ages at the Maaraue in Kostheim, the Diet of Pentecost. Occasion had been the promotion to Knighthood of is both sons Henry hand Frederic, Duke of Swabia. During the Siege of Mainz by Prussian and Austrian troops in the Napoleonic Wars Kostheim had been severely damaged several times. In the cause of the bombing of Mainz in World War II Mainz-Kostheim was subject to air raids.

Conrad (25 April 1228 – 21 May 1254), a member of the Hohenstaufen dynasty, was the only son of Emperor Frederick II from his second marriage with Queen Isabella II of Jerusalem. He inherited the title of King of Jerusalem (as Conrad II) upon the death of his mother in childbirth. Appointed Duke of Swabia in 1235, his father had him elected King of Germany (King of the Romans) and crowned King of Italy (as Conrad IV) in 1237. After the emperor was deposed and died in 1250, he ruled as King of Sicily (Conrad I) until his death.

The House of Zähringen (German: Zähringer, pronounced [ˈtsɛːʁɪŋɐ]) was a dynasty of Swabian nobility. The family's name derived from Zähringen Castle near Freiburg im Breisgau. The Zähringer in the 12th century used the title of Duke of Zähringen, in compensation for having conceded the title of Duke of Swabia to the Staufer in 1098. The Zähringer were granted the special title of Rector of Burgundy in 1127, and they continued to use both titles until the extinction of the ducal line in 1218.

The territories and fiefs held by the Zähringer were known as the Duchy of Zähringen (German: Herzogtum Zähringen), but it was not seen as a duchy in equal standing with the old stem duchies. The Zähringer attempted to expand their territories in Swabia and Burgundy into a fully recognized duchy, but their expansion was halted in the 1130s due to their feud with the Welfs. Pursuing their territorial ambitions, the Zähringer founded numerous cities and monasteries on either side of the Black Forest, as well as in the western Swiss Plateau. After the extinction of the ducal line in 1218, parts of the family's territories reverted to the crown (attained imperial immediacy), while other parts were divided between the houses of Kyburg, Urach and Fürstenberg.