Exploiting divisions for politics

A country that was divided because it is a country of immigrants, with people from all parts of the world, different cultures, different traditions, different languages. But somehow, one ideal that binds them together as a nation.

But that division seems to have been exploited for political ends.

A good leader gets things done in spite of divisions within the ranks.
A great leader unites people in spite of divisions within the ranks.

I don't know what others think, but I think we should really do some research on how this division can and is being exploited. Because we should not be exploited. And knowing how it can be done is the first step toward preventing it from happening again.