It was a idiom because a idiom is a group of words established by usage as having a meaning not deducible from those of the individual words. I don't the man was four times the father or a fighter prince exactly, but he may have acted like so.
Explanation: four, father, fighter. As you may already know alliteration deals with the repetition of sound. All three words begin with the F sound that's why I believe it's alliteration.
