Robert Penn Warren took the title, All the King's Men, from the famous nursery rhyme "Humpty Dumpty," featuring the egg who falls off a wall, gets broken, and can't be put back together. In case you blocked it out of your childhood memories, we reproduce it here:
Humpty Dumpty sat on a wall.
Humpty Dumpty had a great fall.
All the king's horses and all the king's men
Couldn't put Humpty together again.
But anyway, what does a violent nursery rhyme have to do with corrupt southern politics, and a few people trying to do the right thing?
One common interpretation is that Willie Stark is the king and that everybody else in the novel is one of his men (or women, as the case may be). When Willie gets shot by one of his men (Adam Stanton), none of his other men can put him back together.
You could use that interpretation and write a paper about how ironic it is that Dr. Adam Stanton, the person most likely to put Willie back together, kills him. Still, when you know that Huey Long (on whom Willie is based) made a famous speech called "Every Man a King," the Willie as king theory kind of falls down.
But, you probably noticed another possible flaw. This theory requires that Willie be both the King, and Humpty Dumpty. Critic James Rouff argues that Willie is Humpty Dumpty, and not the King (source). He claims that the King is actually God, and that everybody in the novel is one of the God's men. Willie is the guy that tries to reach too high (i.e., to be like God) and ends up getting himself broken beyond repair.
There is a fair amount of evidence to support this thesis. If you like this idea, pick some passages from the text that come to your mind and try to say something interesting about it.
Still, we like the idea of King Humpty Dumpty. Let's break that idea out of its shell, and see if it works. First of all, notice how the King isn't featured in the nursery rhyme. The speaker makes us aware of the (absent) King only by talking about other things that are closely linked to him. If you hear the word "crown," you think of a royal person. In this case, we know the King is lurking somewhere in the vicinity because we see his horses and his men. The horses and men are symbols of the King.
But isn't this story set in the United States of America? There are no kings in America, in the sense that there is no monarch. But there is a different understanding of "king" that might apply to All the King's Men. In America, everybody is supposed to be a king, right? This is the land of equality, or freedom, etc. The founders of America came here to get away from monarchy, to establish democracy.
Is the moral here that if you try to be more of king in America, you'll get knocked off a wall? Well, lots of people try to be king in their own ways in this novel, and lots of people get smacked down. So you could call the title an ironic commentary on America's system of government. It gets even more ironic when we start thinking about the themes of slavery and race in the novel.
But before we go there, we should mention that a "humpty dumpty" is also a not-so-nice term for a rather round person. This explains why the Humpty Dumpty from the nursery rhyme is often drawn as a kind of half man, half egg. They are also extremely fragile, and, once broken, can't be restored.
So, we might ask ourselves, what does this novel show as broken? America, for one thing. The novel asks whether the pieces of America, broken by slavery and unequal distribution of wealth, can ever be put back together again. At the same time, the novel suggests that to put together a broken America, the institutions of slavery, racism, and unequal distribution of wealth also must be broken apart.
This is what Judge Irwin means when he defends Willie by saying, "There's one principal [Willie has] grasped: you don't make omelettes without breaking eggs. […] He's broken plenty of eggs, and he may make omelettes" (3.113). By putting this cliché in a novel virtually devoid of clichés, Robert Penn Warren draws our attention to it, helping us to make sense of the title.