In 1537, Wyatt became a knight. He also began an affair with Elizabeth Darell, who had a son. Afterwards, he was sent to Spain to live in an embassy. His mission in Spain was to improve the relationship between the Holy Roman Emperor, Emperor Charles V, and King Henry VIII of England. Emperor Charles V was unhappy with the King of England because he divorced the Emperor's aunt, Catherine of Aragon. This was especially bad because the King had originally asked the Pope for special permission to marry Catherine, who was the widow of the King's older brother Arthur. The embassy was a disaster. Sir Thomas Wyatt and the other ambassadors, Edmund Bonner and Simon Heynes, were all unsuccessful. Also, Bonner disliked Wyatt. Bonner accused Wyatt of treason (and of liking papists, or Catholics). These accusations were cleared by Thomas Cromwell. Cromwell was the chief minister to Henry VIII and often protected Wyatt.