When Franz Ferdinand's driver took a wrong turn. Archduke Ferdinand was being driven around in Sarajevo. His driver took a wrong turn, and ended up on a side street, where the man who had just tried (and failed) to assassinate Ferdinand happened to be. The assassin took his second chance and killed Ferdinand and his wife, leading ultimately to the First World War.
And that would be pounds to kilos.
Planes measure fuel in weight units not volume!
#10
And no, it was the fleas on the rats that carried the plague!