I have 3 dogs and one is aggressive towards one of the dogs. What should I do?

I have 1 olde english bulldog and 2 pugs. The oldest dog is the male pug, the second oldest is the female pug, and the youngest is a male olde english bulldog.

All three dogs will get in an argument and then the bulldog will go after the oldest male pug. We have had all 3 dogs for over 3 years now and a fight will happen sporadically. They will be getting along great for months and then a fight will break out.

I understand the pack mentality but the problem now is that in the most recent fight the bulldog really hurt the oldest male pug. If I would not of broke up the fight, our male bulldog could have easily killed the pug.

I have heard of this theory of crate and release which we have starting doing but I do not want it to be a permanent solution. We really do not want to surrender our bulldog to another family because he is like a family member to us. There has never been any aggression toward humans.

Do you have any ideas to help the dogs get along all the time?