Steve Lawson’s penalty left 10-man Arbroath rooted to the foot of the cinch Scottish Championship table as Hamilton secured their first league win of the season.
Lawson’s 58th-minute spot-kick sealed a 1-0 victory after Thomas O’Brien had been sent off for handball.
The home side started strongly and threatened when, with Lewis Smith having already gone close, striker Jean-Pierre Tiehi fired just over on the turn with 15 minutes gone.
Smith forced keeper Derek Gaston into a 24th-minute save and Tiehi only just missed the target seconds later as the pressure mounted.
The breakthrough finally arrived 13 minutes into the second half when, after Arbroath’s O’Brien had been dismissed, Lawson, whose shot he had blocked illegally, converted the resulting penalty.
Substitutes Ryan One and Jonny Ngandu both might have doubled their side’s advantage but it was Lawson who went closest to a second goal in stoppage time.