The offices of Master of the Ordnance and Clerk of the Ordnance may be said to date from 1414, when Letters Patent were issued on behalf of Henry V of England to 'Nicholas Merbury, Master of our Works, Engines, Cannons and other kinds of Ordnance for War, and to John Louth, Clerk of the same Works' (though it appears that these were appointments for service in the field of war rather than to a permanent position). Merbury was present at the Siege of Harfleur and (albeit without his guns) at the Battle of Agincourt. By 1450 Master of Ordnance was a permanent appointment, firmly based at the Tower of London.