Was following a truck that was pulling a utility trailer. We had just stopped and started moving again when when he suddenly stopped. I had just sped up maybe going 10 to 15 mph when I applied my brake, the brakes did not engage until after I hit the trailer in front of me and jammed it into truck it was being pulled by.I had front end damage and radiator damage and the car was not drivable. I had noticed previous to this that at times at low speeds the brakes would not engage and would need to be double tapped to get them to engage. Could go weeks without it happening or could happen multiple times in a day. No consistency to the issue.