English Mastiff story.?

My 15 month 140lb English Mastiff is usually a coward and loves all people, even strangers. I never thought he would protect us. We recently moved and had the cable people installing cable. My wife was home alone with the mastiff when the cable was being installed. When the first cable guy got to the house the mastiff refused to leave my wifes side, but wasn't bothering the cable guy, so my wife left the dog inside. The cable guy asked if another cable guy could come meet him at our house so they could go to lunch after the job was done. When the second cable guy showed up he didn't knock, he just walked in the house like he owned it and started to walk towards my wife. Our mastiff jumped on the guy and wrapped his arms around the cable guys kneck and penned him against a wall, and put his nose right in the cable guys face. He never groweled are barked and when my wife pulled him off he was fine. Does anybody else have similar stories about there Mastiff.