John of Gaunt was one of the most powerful English nobles of the fourteenth century. The third surviving son of King Edward III, he played a central role in English politics during the later years of his father’s reign and during the minority of his nephew, Richard II of England ⓘ.

As duke of Lancaster John controlled vast estates and exercised considerable political influence. During the later fourteenth century he acted frequently as a royal councillor and military commander. Through his marriage to Constance of Castile he claimed the crown of Castile and led an expedition to the Iberian Peninsula in the 1380s in an attempt to enforce this claim.

Gaunt’s livery and personal affinities were marked by the emblem known as the Collar of Esses, a chain composed of linked “S” devices. The collar became closely associated with Lancastrian affinity and later with royal authority under the House of Lancaster. Although its precise origin remains debated, it functioned as a visible symbol of allegiance and hierarchical service within Gaunt’s network of retainers. It was subsequently adopted and retained by the Tudor dynasty, where it became a symbol of royal authority rather than merely ducal affinity. 

Gaunt was also associated with several important intellectual figures of his time. During the 1370s he showed sympathy toward the reforming theologian John Wycliffe ⓘ and at times offered him political protection during the controversies surrounding his teachings. 

Gaunt also had indirect family and court connections with the poet Geoffrey Chaucer ⓘ. Chaucer married Philippa Roet, whose sister Katherine Swynford later became Gaunt’s third wife, linking the poet to the Lancastrian household.

Although often controversial within England, John remained an important stabilising figure during Richard II’s reign. His death in 1399 had profound political consequences. Shortly afterwards Richard II confiscated the Lancastrian estates, which prompted John’s son Henry Bolingbroke to return from exile and ultimately seize the English throne as Henry IV of England ⓘ.