The anniversary will be recognised with celebrations ahead of their Ryman League South Division match against Hastings United at Gorings Mead (3pm).
The fixture is certainly apt as the Hornets actually knocked out their Sussex rivals in the fourth qualifying round to book their place in the first round of the competition for only the second time.
That set up the tie with the League side where a record crowd of 7,134 supporters crammed into their former Queen Street home to witness a 3-0 defeat.
Don Rogers, Mel Nurse and Dennis Brown got the goals for the visitors.
To recognise the landmark day, the club has invited some of their old players to Saturday’s match and a number have confirmed they will be in attendance.
Horsham manager Dominic Di Paola added: “Like most clubs we like to mark the memories that have been created. It will be nice to have a few of the former players at the game as it was big achievement in the club’s history.
“It’s another tough game for us and we have a few tough ones coming up now.”
The clash against Swindon was only the second time that Horsham had progressed beyond the qualifying stages of the competition and the first for almost 20 years.
Current Horsham secretary Jeff Barrett was at the game back in 1966 and recalled: “As an excited teenager, I was amongst the 7,134 spectators who squeezed into Queen Street for the Swindon match.
“I arrived as soon as the gates opened resplendent in my newly-acquired Lincoln green and amber rosette and took my place in my usual position in the centre of the terraced stand. Capacity had been increased by the temporary seating behind the Queen Street goal.
“At the time, Swindon were languishing at the bottom of Division 3 but went on to gain promotion before beating Arsenal in the League Cup final two seasons later.
“They had a strong line-up which belied their lowly position including Welsh internationals including Rod Thomas and Nurse.”
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