This is a wonderful set of 19th Century Original English Dueling Pistols originally from England, complete with original gun box.
The rules of a duel followed strict societal codes. If there was no resolution made by the duelers second, then a duel would take place. A duelers second would invite and arrange a duel on behalf of the wronged party, and up until the duel, would attempt to resolve the issue in a nonviolent fashion. If the offender apologized at any point up until the duel, all would be forgiven. If not, then the terms of the duel would be established, such as if they would fight to the death, and how many paces they would take away from each other before firing.
Not as many people died during pistol duels as you might think. Most pistol duels called for only one shot to be fired, and accuracy was difficult and often times the pistols would misfire. Duelers would use a set of dueling pistols, such as this, so that they could fight an even battle. It was considered barbaric to fire more than three shots during a duel.
Learn about the Code Duello.