John Beaufort, 1st Duke of Somerset, 3rd Earl of Somerset (1403-27 May 1444) was an English noble and military commander. Baptised on 25 March 1404, he was the second son of John Beaufort, 1st Earl of Somerset and Margaret Holland, and succeeded his elder brother Henry Beaufort, 2nd Earl of Somerset to become the 3rd Earl of Somerset in 1418. The young earl fought in Henry V's 1419 campaigns in France. In 1421 he accompanied the king's younger brother Thomas of Lancaster, 1st Duke of Clarence to the fighting in Anjou. Thomas was killed at the Battle of Baugé while Somerset and his younger brother were captured. On 25 March 1425, Somerset came into his majority, but the estates of his father had to be managed by his mother for the next thirteen years until he was released from imprisonment.