Henry V, scion of the Frankish Salian dynasty and uncontested King of the Romans since 1106, had inherited both the Investiture Controversy and the Saxon conflict from his father Henry IV.

Upon becoming the new German monarch, Henry V had granted his associate Lothair, son of Gebhard, count of Supplinburg, the Duchy of Saxony in 1106.

In 1110 he had moved to Italy and, after negotiation failed, had captured Pope Paschal II and several cardinals to enforce his coronation as Holy Roman Emperor.

On his return from Rome, he had been immediately excommunicated by the papal legate in Germany, Cuno of Praeneste, and again by Archbishop Guy de Vienne, the later Pope Callixtus II, which encouraged the Imperial princes in their rising against the emperor—most of all the Saxon Duke Lothair of Supplinburg and Archbishop Adalbert of Mainz, Henry's longtime supporter, who after his investiture had deserted him.

Henry had entrusted the Saxon affairs to his field marshal Count Henry of Mansfeld, a Saxon noble himself.

However, though he had had Adalbert imprisoned at Trifels Castle and forced Lothair to submit himself after a court hearing at the Imperial Palace of Goslar, the smoldering Saxon conflict had broken out again in March 1113 over the succession in the Thuringian territories left by late Count Ulric II of Weimar and Orlamünde.

In order to create his own power basis, Henry had made attempts to confiscate the county as a ceased fief but had met with obstinate resistance by Ulric's heir, the Count Palatine of the Rhine Siegfried, son of the Ascanian count Adalbert II of Ballenstedt.

The insurgents gather under the lead of the Osterland count Wiprecht of Groitzsch and the Thuringian count Louis the Springer, but are repulsed by Henry's troops under Mansfeld in a battle at Warnstedt near Thale.

Wiprecht, captured and at first sentenced to death for high treason, is later reprieved, imprisoned at Trifels and divested of his possessions, which pass to the House of Mansfeld.

Emperor Henry's ruthless extension of his power in Germany has produced opposition and revolt, led from 1114 by Adalbert of Mainz and Lothair, duke of Saxony, his former ally.

Lothair had risen in arms against Henry in 1112, but had been easily quelled.

A quarrel in 1113 over the succession to the counties of Weimar and Orlamünde, however, had given occasion for a fresh outbreak on the part of Lothair, whose troops had been defeated at the Battle of Warnstadt, though the duke was soon pardoned.

Having been married at Mainz on January 7, 1114 to the twelve-year-old Matilda, daughter of Henry I of England, to whom he has been betrothed for four years, the twenty-seven-year-old emperor is confronted with a further rising, initiated by the citizens of Cologne, who are soon joined by the Saxons and others.

Henry fails to take Cologne, and his forces had been defeated on February 11, 1115, at the Battle of Welfesholz, denying Henry the power to rule Saxony.

Several nobles, including the deposed Duke Henry of Lower Lorraine and the Saxon bishop Reinhard of Halberstadt, disgusted by Henry's haughty behavior, have joined the insurgents.

Among them is Otto, the eldest son of Adalbert II, Count of Ballenstedt and Adelheid, daughter of Otto I, Margrave of Meissen.

After the death of his father-in-law, Magnus, Duke of Saxony, in 1106, Otto had inherited a significant part of Magnus' properties, and had hoped to succeed him as duke.

However, Lothar of Supplinburg had been named duke in his stead.

In 1112, after Lothar had been banned, Otto had been appointed duke of Saxony by Emperor Henry V; but in the same year, he had come into a dispute with the emperor and had been stripped of his ducal title.

He now allies himself with Lothar to help defeat Hoyer I, Count of Mansfeld, who the Emperor has named duke of Saxony.

According to the chronicles of Pegau Abbey, on February 10, 1115, the Imperial forces gathered at the Kaiserpfalz of Wallhausen and moved about forty kilometers (twenty-five miles) towards Welfesholz (today part of Gerbstedt in Saxony-Anhalt) to meet the united Saxon troops led by Duke Lothair, with first skirmish occurring already on the same evening.

The next day, Henry's commander, Hoyer of Mansfeld, launches an offensive whereby he is killed in a sword combat by the young robber knight Wiprecht II, son of the arrested Count Wiprecht of Groitzsch.

The incident decides the battle: the Saxon armies of Lothair are victorious, forcing Henry's troops to take flight.

In his twelfth-century Chronica Slavorum the Saxon chronicler Helmold describes the battle as "the largest encounter in our time".

The emperor's power to rule Saxony is denied; the Bishop of Halberstadt even refuses a Christian burial of the slain imperial troops.

In November, the Mainz citizens enforce the release of Archbishop Adalbert.

However, Henry can still rely on the loyal support of his Hohenstaufen nephews, Duke Frederick II of Swabia and his brother Conrad III.

When the emperor again moves to Italy for the inheritance of Countess Matilda of Tuscany the next year, Duke Frederick will be appointed regent, which lays the grounds for the rise of the Hohenstaufen dynasty.