Explain: why napoleon was successful in chasing snowball off the farm so quickly and why the other animals did not stop it from happening? you!

Napoleon had been very sly from the outset. It is clear from the differences in opinion between him and Snowball that he saw him as a threat. Since he wanted sole power, he secretly trained Bluebell and Jessie's nine puppies in a loft after having removed them from their mothers once they were weaned. No one realized what his plan was with them at the time. It soon became apparent that Napoleon had been training...

what's that I can't understand;|