In 1971, Rolls Royce went bankrupt, the British postal workers went on strike, and Sean Connery appeared in his final James Bond film. Unbeknownst to the muggle world (and a good part of the magical community, for that matter), 1971 was also the year that the Hogwarts student body formally declared war on Peeves.
Ironically, James Potter and Sirius Black had surprisingly little to do with it.
Eleven new Gryffindors means eleven new kinds of shenanigans. Wish your luck to Professor McGonagall.
Lily's tired of the growing grudge that's taken over Hogwarts. She's tired of the Gryffindor-Slytherin rivalry, of the Marauders and their stupid pranks, of the blood prejudice and even of her best friend, Severus.
James is tired too. He's grown sick of this game of pretend, where everyone acts as if everything's fine when it's really not. His friend group is drifting apart, his grades are plummeting and now there are all these expectations!
Something needs to change this year. Whether that's for the better or the worse is yet to be determined.