Henry of Grosmont was a prominent English nobleman and military leader in the 14th century. Born around 1310, he was the first Duke of Lancaster and played a significant role in the Hundred Years' War against France. His lineage was tied to the royal family, as he was the son of Henry Plantagenet, the Earl of Lancaster. As a skilled commander, Henry of Grosmont participated in various military campaigns and was known for his loyalty to the English crown. He was also a key figure in the development of the Lancastrian dynasty, which would later influence English history through figures like Henry IV.