Man's Best Friend Forever?

Me and my eskie mix were on a walk when this dog ran up to me growling and showing his teeth before he lunged for my stomach. All I could do was close my eyes and hold up my hands because I was so scared and only eleven! Then when I opened my eyes I realized my dog had jumped on top of the dog and was now snapping at him as he ran a circle around me still trying to get to me!! This lasted like two minutes before his owner grabbed him. This dog was twice my dogs size and she had never ever showed any agrression before and hasn't since! I love her so much!