Photos #14-#26 depict an 18th-century duel. What is that? It is an arranged engagement in combat between two people, with matched weapons, following agreed-upon rules. Each person was accompanied by at least one person, called a "second." It is part of a code of honor.
In this portrayal, it was first agreed upon to use pistols (the seconds helped) but switched to muskets. Both fired. No one was killed or maimed, so both parties' honor was restored.