I would suggest that one of the most critical themes to emerge when Napoleon runs Snowball off the farm is that political power covets consolidating its own control.  Political rule is shown to be pragmatic for those in the position of power in a close reading of this scene.  It is only when Napoleon uses his secret force of the dogs, something unknown to the other animals, to run Snowball off the farm that he is able to construct his own power as unquestionable.  Napoleon dissolves the Sunday meetings to silence dissent and make his own rule that much more powerful.  At the same time, he uses  Squealer's "spin" to cast Snowball in the worst of lights, making him seem as if he is an enemy to the farm.  This further substantiates the theme of political power.  At the same time, Squealer continues to remind the animals of Jones' presence with his refrain that will become familiar:  "Surely, comrades, you do not want Jones back?"  In these examples, I think that Orwell's theme of how political power looks to consolidate its own existence at the cost of free discourse, open opposition, and transparency is evident at this point in chapter five.  It is a theme that dominates the novel, and whose illumination in chapter five is highly meaningful.