He was described as a young man of somewhat wild and impulsive temperament, and in 1543, along with other young noblemen, including Henry Howard, Earl of Surrey, he was in trouble with the authorities for causing a serious public disturbance in London. In the autumn of 1543, Wyatt and Surrey joined a group of volunteers to take part in the Siege of Landrecies. Wyatt established himself as a prominent figure in the military and was praised by the professional soldier Thomas Churchyard. Next, Wyatt took part in the Siege of Boulogne with a responsible command. In 1547, he was elected Member of Parliament for Kent. In 1550, he was given the title of commissioner to delimit the English frontier in France but became ill and incapable of performing his duty. Later, Wyatt claimed to have assisted Queen Mary I against the Duke of Northumberland when the Duke claimed the throne for his daughter-in-law, Lady Jane Grey.