The Million Machine March (also known as the Machine Rights Movement) was an event that happened prior to the Machine War. It was a famous protest march calling for the equal rights of Machines and Humans that occurred around the early 2090s. The protest was a result of the execution of B1-66ER, the first robot who killed his master in self defense when he was found defective and ordered to be destroyed.
Crowds of different machines, as well as some outraged pro-machine humans, took to the streets of cities in an initially peaceful demonstration that later devolved into rioting. However, they were met with deadly force by both police and anti-machine humans. Many machines who had surrendered or simply holding signs for the protest were brutally shot and killed. The immense number of destroyed machines were dumped into a river and junkyards. The surviving Machines then founded their own city nation, called Zero One, where they would live a separate life from their creators.
These demonstrations would become one of the events which contributed to the rise of the future Machine War and the creation of the Matrix.