why is it called Black Friday?

What I am led to believe is this.
A long time ago, when the route to the holy land was guarded for the travel of pilgrims to visit the holy city, by the Knights Templar. The pope at the time became very jealous and fearful of their great name and power. They had all become very powerful. He declared them to be criminals and rapers and pedophiles etc. They were rounded up and put to death. It was Friday the 13th. It became known as Black Friday. Black Friday is also used for other unfortunate events. Here in Australia, a while ago, a huge bushfire swept through this state, destroying so much and killing so many people, it became known as Black Friday.
If I have the story of the Knights Templar all mucked up, someone please correct me.