In 1115, the young Empress Matilda, wife of Holy Roman Emperor Henry V (1081-1125), fourth Emperor of the Salian Dynasty, gave birth to a healthy son, named Henry in honor of both his imperial father and his grandfather, King Henry I of England.
When his uncle, William Adelin, drowned at the White Ship disaster in 1120, the young prince Henry suddenly become the next-in-line to the throne of England. While King Henry I remarried in 1121 to Adeliza of Louven, the daughter of Godfrey I of Leuven, this marriage was childless, and in 1122 Henry I declared the then 6-years-old german prince as his heir.
When he was but 10 years of age, his father, Emperor Henry V, died. The Archbishop of Mainz convinced many nobles to support Lothair, Duke of Saxony, as Emperor. But this bid failed, not only because of the existence of legitimate heir, but also due to the action of the fearsome King of England, who landed in northern germany, officially to "pay his respects" to his deceased son-in-law, but actually to ensure the inheritance of his grandson and heir.
The Holy Roman Empire soon had a 10-years-old King of Germany, and an Imperial Regency Council was formed, composed of his kinsmen, Frederick II of Hohenstaufen, Duke of Swabia, and Conrad III, Duke of Franconia, Empress Matilda, King Henry I of England, and also by Henry X, Duke of Bavaria, after his marriage to Empress Matilda on 1128.
The rebellious Duke of Saxony signed a peace treaty with the Regency Council in 1126, and Lothair's 8-years-old daughter and heiress, Gertrude of Supplinburg, became engaged to the young King of Germany.
The marriage occurred in the following year, and the young couple was later sent to England, where Henry lived from 1127 to 1132 in his grandfather's court. His stay in the court of the Lion of Justice greatly shaped him. The young King learned the importance of a centralized government, and of Henry I's social and judicial reforms. When in 1130, during the papal controversy, Pope Innocent II and Antipope Anacletus II attempted to influence the young King of Germans, they found a determinate and focused men. While Henry VI was naturally inclined to support Innocent's claim to the papal throne, he first made sure that Innocent II confirmed his Imperial Investiture Rights, and gave up the papal claims to the allodial property left to the Pope by Matilda of Tuscany in 1115. These same lands were then granted to the Emperor's father-in-law, Henry X of Bavaria, who became also the Margrave of Tuscany.
It was also during their stay at the english court that Gertrude gave birth to their first child, Matilda of Rouen (1131-1174).
Two years later, the now-adult Henry VI raised an army and distinguished himself against Roger II of Sicily, Antipope Anacletus II's greatest supporter, and, in the following year, was crowned Emperor by Pope Innocent II. The Sicilian Campaign was halted in January 1136, when, after receiving news of the death of his grandfather, Emperor Henry VI hastily signed a peace treaty with Roger II of Sicily.
Henry VI arrived in England in march of the same year, and was soon crowned at Westminster Abbey as King Henry II of England. It would be during their stay in London that Empress Gertrude gave birth to their first son and heir, Henry of Westminster (1136-1182). As King of England, Henry II continued his grandfather's works, ensuring a strong, centralized and wealthy England1. He also used of his Investiture rights to form a Lay Priest bureaucracy, forming a centralized government across the Empire.
In 1138 Empress Gertrude gave birth to their second son, Lothair of Northeim (1138-1162), named in honor of the empress's recently diseased father. Two years later was born their fourth child, Richeza of Süpplingenburg (1140-1160).
Empress Matilda was once more widowed in 1139, after the death of Duke Henry X of Bavaria, known as Henry the Proud. Emperor Henry VI declared himself guardian of his 1-year-old half-brother Henry2, the infant Duke of Bavaria and Margrave of Tuscany. While this move allowed Henry VI to control the resources of Bavaria and Tuscany, which greatly increased his power, he was deeply found his younger brother. When, in 1148, Renauld III, the rebel Count of Burgundy, who had, eighteen years before, attempted to proclaim the independency of Burgundy from the Empire, died, he engaged his brother to Beatrice, Renauld's 3-years-old heiress.
Emperor Henry VI become widowed on April 13, 1143, as Empress Gertrude died a couple of months after giving birth to their last daughter, Gertrude of Nuremberg (1142-1197). Having loved her deeply, and already having two healthy sons to ensure his lineage, the Emperor refused to remarry, remaining loyal to her memory.
In 1146, Bernard of Clairvaus started preaching for the Second Crusade. When the Emperor, who was then in England, heard about Bernard's preaching, he promptly supported the crusade, giving his blessing to all his vassals who desired to take the cross, although he declined to join. As an explanation, he declared that, while he could not "leave his land at the mercy of faithless enemies". Both his uncle, Duke Conrad III of Franconia, and his cousin, the future Duke Frederick III of Swabia, took the cross.
Later, it became a constant rumor that the Second Crusade could have successfully liberated Jerusalem if only Emperor Henry VI had taken the cross. The Emperor's diplomatic skills, witch allowed for the german crusaders to travel trough sea across the enemy Kingdom of Sicily, could have avoided surely aided, stopping the disunion and leadership clashes which doomed the Crusade. We'll never known.
Nonetheless, many agree, grumbling, that Emperor Henry VI was only capable of maintaining the complete extension of his possessions if he had been not only present, but also constantly traveling through them. Only an energetic, fearless, obsessive and, to use a modern term, a workaholic3 like Henry VI could have kept united such distant lands as then were Germany, England and Normandy.
Emperor Henry VI arranged the marriage of his oldest son, Henry of Westminster, to Judith of Lorraine (1140-1173), daughter of Duke Matthias I of Lorraine, marriage which occurred in 1152. Two years later, Henry of Westerminster left to Milan, where the Archbishop crowned him as King of Germany. This ensured the succession when Henry VI suddenly died4 in 1160.
Unlike previous Emperors, Henry VI left all his possessions to his firstborn son, Henry of Westerminster.
1 The consequences were far-reaching. Without the anarchy of OTL, the English barons were further weakened, avoiding the Baron Revolt of 1173-1174. Unlike OTL Henry II, TTL Henry II (also Emperor Henry VI) recognized Malcolm IV of Scotland as Earl of Cambria and the future William I of Scotland as Earl of Northumbria.
2 Duke Henry XI of Bavaria (1138-1175) was a paradoxical man. A remarkable theorist who left many great philosophical treaties, he was also known as a deeply violent man. Henry the Bull was known for falling in fits so fearsome, and for inflicting such atrocities in his enemies, that the mere thought of having to face his wrath caused many dissatisfied dukes to dutifully obey his half-brother and suzerain, Emperor Henry VI.
3 Records stat that, constantly, Emperor Henry VI worked through sleepless nights, working on some problem or another. He surely spent little time on himself, having once declaring that he found only joy in the challenge of rulership.
4 Emperor Henry VI was simply found dead a certain morning at his castle in Northeim by a servant. It was determinated that he had died of natural causes (most likely a hearth-attack), although rumors of poisoning appeared from time to time.