That's Representative John Lewis in both pictures. In the first, he's being beaten by a member of the Alabama State Police for failing to disperse. In the second, well, the point is obvious, isn't it?
By the way, this is what happened in Selma in 1965:
You can read The President's remarks here.
What greater expression of faith in the American experiment than this, what greater form of patriotism is there than the belief that America is not yet finished, that we are strong enough to be self-critical, that each successive generation can look upon our imperfections and decide that it is in our power to remake this nation to more closely align with our highest ideals?That's what happened yesterday.