BLM began as a hashtag in 2013 after the acquittal of George Zimmerman, but it began in earnest in 2014 after the shooting death of Michael Brown. In 2012, 48 law enforcement officers were feloniously killed in the line of duty, and over 52,000 officers were assaulted. It's amazing how BLM used their time machine to go back in time and cause people to assault and kill police officers. And considering that police are infallible gods, it's just crazy. 

https://ucr.fbi.gov/leoka/2012/officers-assaulted/assaults_topic_page_-2012