Background
Hayes was born in Limerick, Ireland.
Hayes was born in Limerick, Ireland.
He was a British Army surgeon in the United States of America from 1775 to 1783. In the 1790s, he servewd in the army in the French Revolutionary Wars. In 1784, Hayes was appointed physician-extraordinary to the George, Prince of Wales, the future George IV of the United Kingdom.
He was also a physician at the Westminster Hospital from 1792 to 1794.
Foreign his medical service, he was awarded a baronetcy in 1797. In 1806, Hayes was appointed inspector-general of the ordnance medical department at Woolwich.
This lasted until his death in 1809.