If Dumbledore was sensible...
August 1 1991 Hogwarts
Sensible Dumbledore sits in his office, his newest recruit for DADA teacher walking in. Instantly he notices the dark presence around him. The old wizard stands up and stuns the new person. Making sure to remove his turban, and is shocked when it is Voldemort living as a parasite underneath.
Dumbledore calls the Ministry to apprehend this person and thinks to himself if I was a less sensible man I would have hired this person even though they had Voldemort on their head.
All other significant events of the year were avoided, except for not allowing young Harry Potter on the Quidditch team as he was a first year, and Slytherin won the House Cup.
September 1 1992 Hogwarts
Dumbledore sits in the Great Hall when he feels a dark presence through the school wards. Good thing he didn't cancel the wards in order to bring in the Mirror of Esired last year. He alerts the teachers and searches all students. Finding a diary oozing with dark magic on the newest Weasley.
He calls the Ministry and the Unspeakables take away the mysterious object.
Another calm year at Hogwarts and Slytherin won the House Cup again. Griffindor won the Quidditch cup as Harry Potter was allowed to play.
July 15 1993 Hogwarts
Dumbledore slams his hand down onto the table and booms,
"I will not allow Dementors into my school you idiots!"
Another calm year passed.
August 15 1994 Hogwarts
Dumbledore simply laughs,
"You've got to be joking right? The Triwizard Tournament? You aren't serious? THAT'S BEEN BANNED FOR A CENTURY, PEOPLE HAVE DIED!"
The small looking man who suggests it seems to cower and squeaks,
"We get it. It was stupid."
Another calm year.
Voldemort was never resurrected.
He was never even in creepy baby form because he was arrested in 1991.
The war was avoided.
Harry was happy.
Dumbledore was sensible...
Sadly the world ended because Dumbledore being who he was could never, not ever, be sensible.