Anger is literally an umbrella emotion.
Anger only exists because other feelings and such (spokes) hold it up.
Like an umbrella, in most cases it a defense.
Supporting the spokes of any umbrella is the main shaft, which in the case of anger, is injustice.
Any time you feel anger, there is some sense of "injustice" to it. Granted many times it can be a false sense or even a broken sense of injustice, but it's there.
The words I see people here using, which eaisily connect to a sense of injustice are: invalidated, threatened, hurt, disrespected, etc. Others that would connect to those are being made to feel, less than others, unworthy, unwanted, worthless.
When we've been wounded though, like a beaten dog forced into a corner, our response to those situations is often over the top or out of proportion to the situation at hand. If we can see and identify what's going on, even as it happens we can correct and only apply the amount warranted for the situation.
Easy? Nope, I struggle with anger issues and freely admit to having a really bad temper.... it's better than it was 5 years ago..... but still have quite a long way to go.