The 2022 Bahrain and Australian GP winner was on his third lap aboard the 1972 Ferrari 312B3 as part of a parade alongside ex-Ferrari driver and six-time Le Mans 24 Hours victor Jacky Ickx.
Leclerc headed out for a slow sighter lap but soon picked up the pace and on his third lap lost the rear of the 312B3 into the famous La Rascasse right-hander.
The Monaco resident backed the car into the barriers and dislodged the car’s rear wing. He immediately gesticulated with his hands to intimate a problem with the pedals.
Leclerc did resume before long but pulled up on the main straight with smoke wafting from the rear of his car, and Ickx stopped a little further up the road in his earlier 312B.
A frustrated-looking Leclerc and a pair of marshals inspected the damage before chatting with Ickx.
Leclerc was recorded saying: “I lost the brakes. I lost the brakes! I braked, the pedal was hard, and it went to the floor.
“I was lucky to have it at that moment, because if I had had it at another place, it was no good… the problem is that I got scared. I arrived normally in the corner.”
He later tweeted: “When you thought you already had all the bad luck of the world in Monaco and you lose the brakes into rascasse with one of the most iconic historical Ferrari Formula 1 car.”
The 312B3 was, somewhat ironically, the flat-12-powered car that prompted Ickx to quit Ferrari following the 1973 Italian GP due to poor reliability and performance.
Its developed ‘-74’ successor was then driven by Lauda and Clay Regazzoni to second in the constructors’ championship title in 1974, falling behind the McLaren M23.
The high-airbox 312B3 Leclerc was driving is owned by Methuselah Racing, which is based in Cologne and headed up by Mario Linke.
This chassis was down on the entry list to contest the race for three-litre grand prix cars built from 1973 to 1976, where it would be driven by Claudia Hurtgen.
Former Abt Cupra Extreme E driver Hurtgen was a late stand-in for the Monaco Historic but won the earlier pre-1961 front-engine race aboard a Methuselah-run Ferrari 246 Dino.
That event was red flagged, ensuring Hurtgen of the spoils at a venue where the then up-and-coming Formula 3 racer rolled in 1993 and severely damaged her hand to effectively end a single-seater career that had the potential to reach F1.
The 312B3 dropped by Leclerc was a different chassis to the 312B3 that ex-Ferrari F1 driver Jean Alesi shunted last year in the Monaco Historic when he was embroiled in a controversial tangle with the Lotus 77 of triple Le Mans winner Timo Werner on the home straight.
Leclerc, who famously set pole at Monaco in 2021 before crashing and missing the F1 race due to the subsequent car damage, had been out in another historic GP car earlier last month.
To mark the 40th anniversary of the death of Gilles Villeneuve, Leclerc had been driving the Canadian’s revered 312T from 1973 around Fiorano.
Asked by Motorsport.com about that experience, Leclerc said: “It was very special.
“The cars were very different back then.
“As soon as I got into the car you can really feel that the safety that we have now is just incredible and back then to push so much those cars with so little safety, you have to be quite mentally strong.
“It was nice and very playful also as a car so it was cool.
“The tyres were the same ones that they had on the car in the museum for I don’t know how many years, so it was like wood!”