“Bill leads the city in saluting the victory over the Dead Rabbits, and he makes plans to kill the Butcher during this ceremony, in front of the entire Five Points community, in order to exact public revenge.”
I picked this off of Wikipedia because i felt this is a turning point in the movie. After a long battle that killed tons the victory was a great achievement. But now Bill wanted to kill the Butcher in front of tons of people in the community. This is a bad sign of things to come because if he does this then a bloodbath will start. The fighting will continue and they will search for Bills head. Also they would want to get revenge on him as well. 