Though his political and military achievements have a certain historical importance, he is best known as the earliest troubadour—a vernacular lyric poet in the Occitan language—by whom some work survives.

[2][3] His birth was a cause of great celebration at the Aquitanian court, but the Church at first considered him illegitimate because of his father's earlier divorces and his parents' consanguinity.

This obliged his father to make a pilgrimage to Rome soon after his birth to seek Papal approval of his third marriage and the young William's legitimacy.

The Duchess was an admirer of Robert of Arbrissel, and persuaded William to grant him land in northern Poitou to establish a religious community dedicated to the Virgin Mary.

In September 1101, his entire army was destroyed by the Seljuk Turks led by Kilij Arslan I at Heraclea; William himself barely escaped, and, according to Orderic Vitalis, he reached Antioch with only six surviving companions.

William was excommunicated a second time for "abducting" the Viscountess Dangereuse (Dangerosa), the wife of his vassal Aimery I de Rochefoucauld, Viscount of Châtellerault.

Relations between the Duke and his elder son William also became strained—although it is unlikely that he ever embarked upon a seven-year revolt in order to avenge his mother's mistreatment, as Ralph of Diceto claimed, only to be captured by his father.

Ralph claimed that the revolt began in 1113; but at that time, the young William was only thirteen and his father's liaison with Dangereuse had not yet begun.

[8] William's greatest legacy to history was not as a warrior but as a troubadour—a lyric poet employing the Romance vernacular language called Occitan, or formerly Provençal.

The song traditionally numbered as the eighth (Farai chansoneta nueva) is of dubious attribution, since its style and language are significantly different (Pasero 1973, Bond 1982).

An anonymous 13th-century vida of William remembers him thus: The Count of Poitiers was one of the most courtly men in the world and one of the greatest deceivers of women.

In a striking departure from the typical attitude toward women in the period, William seems to have held at least one woman in particularly high esteem, composing several poems in homage to this woman, who he refers to as midons (master):[9] Every joy must abase itself, and every might obey in the presence of Midons, for the sweetness of her welcome, for her beautiful and gentle look; and a man who wins to the joy of her love will live a hundred years.

He is among the first Romance vernacular poets of the Middle Ages, one of the founders of a tradition that would culminate in Dante, Petrarch and François Villon.

Guillaume, writing a century earlier, is just as much of our age as of his own.William was a man who loved scandal and no doubt enjoyed shocking his audiences.

One of William's poems, possibly written at the time of his first excommunication, since it implies his son was still a minor, is partly a musing on mortality: Pos de chantar m'es pres talenz (Since I have the desire to sing,/I'll write a verse for which I'll grieve).

These might be the first "Crusade songs": Then the Poitevin duke many times related, with rhythmic verses and witty measures, the miseries of his captivity, before kings, magnates, and Christian assemblies.

[14] Armenian sources, Basil the Doctor and Gregory the Priest, imply that Baldwin of Marash was a son of William and Philippa, born shortly before the latter's retirement to a convent in 1114.