currently at the top of .world. Comments are full of either people pointing out actual communist positions on the matter, or just botslop.
You're mixing two things together i think. After Marx refused Willich's challenge, an associate of Marx (Schramm) challenged Willich to a duel to defend Marx's honour. However duels were illegal in England, so they went to Belgium to actually fight the duel. Willich shot Schramm in the head, but he survived.
Wilich emigrated to the US a couple years later