Can they legally charge me and set up a court date for an incident i was never questioned on or arrested for?

I received a letter in the mail from the city court house stating I had to appear in court on specific date. The letter contained a case number but did not say what it was for. I looked it up online and said I had to appear in court for assault. Prior to this court notice I was not contacted by any police, questioned about the incident or arrested. I am assuming it was over an argument at a bar that may have lead to someone getting hit. Everyone at the bar was intoxicated and nobody actually saw the supposed victim get hit. Through hearsay I was told after I had left the bar that night, police showed up and spoke with the supposed victim and their friends. The "victim" claimed I assaulted her but she had no marks. This said incident happened three months ago. I was never once questioned, arrested or informed by the police. I only learned of my supposed guilt from the court appearance letter. The victim and I had arguments prior to this after she confused me with someone else.