Southern League Premier Division side Chesham strode into round two at the expense of League Two Bristol Rovers after a Ryan Blake's strike did the damage.
Chesham, who sit 75 places below Rovers in the football pyramid, last made the first round of the FA Cup in 1994.
Victory sees the Generals progress to the second round for only the second time in their history, the first coming in 1980 when they were knocked out in the third round by Cambridge United.
Former Rovers striker and current Chesham player-coach Barry Hayles was given a warm ovation when he appeared as a 72nd-minute substitute, minutes before he supplied the assist for Blake's winner.
Elsewhere Port Vale succumbed to a 94th minute leveller by Maidstone, last year's Cup giant-killers Bradford were held by Aldershot and Oxford will need a replay to beat National League side Braintree.
The draw for the 2nd round takes place on Monday night.