Henry's son, also named Henry, was born at the castle of Grosmont in Monmouthshire between 1299 and 1314. According to the younger Henry's memoirs, he was better at martial arts than academic subjects and did not learn to read until later in life. Henry was coeval with Edward III and was pivotal to his reign, becoming his best friend and most trusted commander. Henry was knighted in 1330, represented his father in parliament and fought in Edward's Scottish campaign. After the outbreak of the Hundred Years' War, Henry took part in several diplomatic missions and minor campaigns and was present at the great English victory in the naval Battle of Sluys in 1340. Later, he was required to commit himself as hostage in the Low Countries for Edward's considerable debts. He remained hostage for a year and had to pay a large ransom for his own release.