Born in Orbe Castle, Orbe, Kingdom of Upper Burgundy (now in modern-day Switzerland), she was the daughter of Rudolf II of Burgundy, a member of the Elder House of Welf, and Bertha of Swabia. Her first marriage, at the age of fifteen, was to the son of her father's rival in Italy, Lothair II, the nominal King of Italy; the union was part of a political settlement designed to conclude a peace between her father and Hugh of Provence, the father of Lothair. Their daughter, Emma of Italy, was born about 948.
The Calendar of Saints states that her first husband was poisoned by the holder of real power, his successor, Berengar II of Italy, who attempted to cement his political power by forcing her to marry his son, Adalbert; when she refused and fled, she was tracked down and imprisoned for four months at Como.
According to Adelaide's contemporary biographer, Odilo of Cluny, she managed to escape from captivity. After a time spent in the marshes nearby, she was rescued and taken to a "certain impregnable fortress," likely the fortified town of Canossa near Reggio. She managed to send an emissary to Otto I, and asked the East Frankish king for his protection. The widow met Otto at the old Lombard capital of Pavia and they married in 951. Pope John XII crowned Otto Holy Roman Emperor in Rome on February 2, 962, and, breaking tradition, also crowned Adelaide as Holy Roman Empress.
In Germany, the crushing of a revolt in 953 by Liudolf, Otto's son by his first marriage, cemented Adelaide's position, for she retained all her dower lands. She and their eleven-year-old son, the crown prince who became Otto II, accompanied Otto in 966 on his third expedition to Italy, where Otto restored the newly elected Pope John XIII to his throne (and executed some of the Roman rioters who had deposed him). Adelaide remained in Rome for six years while Otto ruled his kingdom from Italy. Their son Otto II was crowned co-emperor in 967, then married the Byzantine princess Theophanu in April 972, resolving the conflict between the two empires in southern Italy, as well as ensuring the imperial succession. Adelaide and her husband then returned to Germany, where Otto died in May 973, at the same Memleben palace where his father had died 37 years earlier.
In 983, her son Otho II died and was succeeded by her grandson Otho III under the regency of his mother Adelaide's daughter-in-law Dowager Empress Theophanu. When Theophanu died in 991, Adelaide assumed regency on behalf of her grandson the Emperor until he reached legal majority four years later. Adelaide resigned as regent when Otho III was declared of legal majority in 995.
Adelaide had long entertained close relations with Cluny, then the center of the movement for ecclesiastical reform, and in particular with its abbots Majolus and Odilo. She retired to a nunnery she had founded in c. 991 at Selz in Alsace.
On her way to Burgundy to support her nephew Rudolf III against a rebellion, she died at Selz Abbey on December 16, 999, days short of the millennium she thought would bring the Second Coming of Christ. She had constantly devoted herself to the service of the church and peace, and to the empire as guardian of both; she also interested herself in the conversion of the Slavs. She was thus a principal agent—almost an embodiment—of the work of the pre-schism Orthodox Catholic Church at the end of the Early Middle Ages in the construction of the religious culture of Central Europe. Some of her relics are preserved in a shrine in Hanover. Her feast day, December 16, is still kept in many German dioceses.
In 947, Adelaide was married to King Lothair II of Italy. The union produced one child:Emma of Italy (born 948), queen of France and wife of Lothair of France
In 951, Adelaide was married to King Otto I, the future Holy Roman Emperor. The union produced four children:Henry (born 952)
Bruno (born 953)
Matilda – born 954, the first Princess-Abbess of Quedlinburg
Otto II (born 955), later Holy Roman Emperor
Lotario is an opera seria in three acts by George Frideric Handel. It is a fictionalisation of some events in the life of Adeläide.
Adelaïde is the heroine of Gioacchino Rossini's 1817 opera, Adelaide di Borgogna and William Bernard McCabe's 1856 novel Adelaide, Queen of Italy, or The Iron Crown.
Adelaide is a featured figure on Judy Chicago's installation piece The Dinner Party, being represented as one of the 999 names on the Heritage Floor.