Gangs of New York ending explained (spoilers)

[arthur]

Amsterdam gets to be best friends with The Butcher who had earlier killed Amsterdam's father, until The Butcher realises Amsterdam is the Priest's son. There is then a big riot between the rival sides with Amsterdam leading his father's gang. Amsterdam kills The Butcher, who is then buried next to The Priest (Amsterdam's father), because Amsterdam knew of the respect that the Butcher had for The Priest.