"I will work harder!"
In this propaganda boxer persuades the other animals to work as hard as he did. Because Napoleon corrupted boxers mind that he was always right. So boxer as a well respected animal told the other animals he would work harder to get them to work harder with him. This bandwagon propaganda is bandwagon because boxer is a loyal character the other animals will what he does and says. That's why Napoleon and squealer focus on corrupting boxer.