In Animal Farm, is the transition in control from Snowball to Napoleon the turning point from sound leadership to corruption?

's expulsion
is the major turning point, as this givesfreedom to institute his decisions without debate.
However, the corruption of power in the farm was seen much earlier, when the pigs decided that
they should receive a better portion of food than the other animals. Setting the milk and
windfall apples aside for the pigs is the first overt clue that the balance of power and
privilege is not as equal ashad wanted:

"Milk and
apples (this has been proved by Science,...