The Surveyor-General of the Ordnance was a subordinate of the Master-General of the Ordnance and a member of the Board of Ordnance from its constitution in 1597. Appointments to the post were made by the crown under Letters Patent. His duties were to examine the ordnance received to see that it was of good quality. He also came to be responsible for the mapping of fortifications and eventually of all Great Britain, through the Ordnance Survey, and it is this role that is generally associated with surveyor-generalship.