This timeline diverged from our own in 1198 when Emperor Heinrich VI von Hohenstaufen declared the title of Holy Roman Emperor to be hereditary to the Hohenstaufen Dynasty. Later Hohenstaufen emperors would carry on the task of establishing a centralized Holy Roman Empire by means of expanding the Hohenstaufen dynasty's holdings inside Swabia. This expansion of the royal domain mimics that which took place in France during the late middle ages (Which in frances case was one of the key methods used to centralize the kingdom). The Swabian Order of Knights was established in 1270 by Adolf I von Hohenstaufen, serving as his personal army loyal only to him. Legal reforms in the 1354 created the Imperial Diet (A permanent court similar to a parliament), which allowed for a more bureaucratic administration of the empire, another key step in centralization. By 1440, the Hohenstaufen Domain encompassed most of the duchy of Swabia, and the Emperor Adolf III was now in a position to begin reforming the Holy Roman Empire itself.
Many struggles laid ahead for the Hohenstaufen dynasty, however. The reformation of the Catholic Church in the early 16th century resulted in the German Wars of Religion. These bloody conflicts ultimately resulted in the confiscation of all protestant lands inside the empire, which were subsequently redistributed to Catholic dukes at the diet of Nuremberg in 1597.
By the mid 17th century the Holy Roman Emperor was at the forefront of all European affairs and was the dominant power in Western Europe, rivalled only by Czar of Russia himself. In the year 1697 Holy Roman Emperor Friedrich VI summoned the princes of the Holy Roman Empire to a diet at Aachen. Here he instituted massive legal reform aimed at ending the autonomy of the nobility inside the Holy Roman Empire.
The Roman Empire had been restored.
1198: Heinrich VI passes the Erbreichsplan at the Diet of Aachen, thus ending the elective monarchy of the Holy Roman Empire. The title of Emperor now passes hereditarily. Minor concessions made to nobility.
1204: The Fourth Crusade is launched by Venice, and backed by the Holy Roman Empire, against the Byzantine Empire. The Eastern Roman Empire is dissolved, and a new "Latin Empire" is founded in its place.
1208 - 1212: The Imperial-Guelf conflict between Heinrich VI von Hohenstaufen and Otto IV von Guelf (Plus their respective supporters) started when Otto IV raised his flag in rebellion against the Emperor in opposition to the Erbreichsplan. Otto IV both wanted to claim the Imperial Throne and also to reduce the Hohenstaufen dynasty growing influence inside the Empire. The conflict lasted 4 years, and ultimately resulted in the Imperial party's victory. All Welf possessions in Bavaria are confiscated by the Hohenstaufen Dynasty, and subsequently incorporated into their domain.
1212 - 1220: After Hohenstaufen Castle was destroyed in the Guelf Rebellion, Heinrich VI used lands confiscated from Otto IV to build a new castle at Nuremberg. This city would eventually become the Capital of the Empire.
1225: When his Father Heinrich VI died, Friedrich II took the Imperial Throne. Although previous emperors had made the journey to Rome in order to be crowned, Friedrich II demanded that the Pope travel to Germany to Crown Friedrich. When the Pope refused, Friedrich II excommunicated the Pope, removed him from office, and set up a new pope in his place. This act firmly established Friedrich II above the Papacy, renewing the age old tensions between Emperor and Pope.
1245: The Swabian Bull of 1245 was a legal document which explicitly listed and expanded the Hohenstaufen demesne (lands hereditary to the family) inside Swabia. Also listed in the document was the holdings of all other dukes, counts, and barons in Southern Germany. This document can be seen as a direct imitation of the Doomsday Book (A similar document made in England in the 11th century). By the Swabian Bull, 50% of the Duchy of Swabia became part of the Hohenstaufen demesne.
1254: Conrad II is crowned Holy Roman Emperor. His reign focused primarily on squashing German rebellions. Conrad also passed many reforms, including the standardization of measurements and weights, the destruction of multiple rebellious dukes' castles, and the institution of the first gold based tax in the history of the Empire. By this point, a money economy was returning to Europe, towns were growing, and with them a new middle class of literate, skilled workers.
1291 - 1304: The tensions raised during Friedrich II's and Conrad II's reign between Emperor and pope reached a breaking point when Adolf I again demanded the Pope to travel to Germany for his Coronation. The Welf Dynasty allied itself with the Papacy, as did many Lombard cities, forming what is now known as the Second Lombard League. Adolf's forces were raised from his vast personal holdings in Swabia and from the hundreds of Free Imperial Cities across Germany. By the end of the war, both factions were exhausted, and signed a compromise in Milan. This compromise gave the prominent Italian Cities nearly complete autonomy in return for a special tax on trade goods. The Pope was separated from Imperial elections and coronations completely.
1315: The rise of the Sultanate led by Osman I was a matter of grave concern to the weak Latin Empire, and thus to the HRE as well. Emperor Adolf I called for a crusade against the Ottoman Turks in 1309 after their conquest of Nicea. The crusade halted Ottoman expansion to the west for the next century.
1320: The Golden Bull of 1280 was a legal decree issued by the Imperial Diet at Nuremberg headed by the Emperor which fixed important aspects of the constitutional structure of the Holy Roman Empire. The Holy Roman Empire would be divided into 6 Imperial Circles for administrative purposes, each one having its own (limited) courts. The Reichstag was established as the Legislative body of the Empire, headed by the Emperor and also consisting of the hundred largest landholders in the Empire, as well as one vote from every "Free Imperial City" (Cities placed under the direct rule of the Emperor). Due to the inclusion of the Free cities, the Holy Roman Emperor would have a solid supporter base inside the Reichstag (the Free cities generally approved of centralized power and the weakening of larger territorial princes). The Holy Roman Emperor would remain the feudal overlord of all his subjects inside the Holy Roman Empire, and would now collect a special tax from all territories represented in the Reichstag.