After an attempt at bribing Strickland didn't work, Biff and his gang, Match, Skinhead and 3-D, got drunk and devised a plan to get back at Vice Principal Strickland.
Vice Principal Strickland received a box of cigars with a card that claimed they were from someone thanking him for standing up to Biff Tannen. He lit one in his office at the Hill Valley High School, and Biff took a photograph of him through the window. The cigar exploded in his face, and his office caught on fire. He tried to use a fire extinguisher to put the fire out, but Biff rigged it to accelerate the flames instead. Strickland rushed all of the teachers and students out of the school, and Biff sent the photograph to the authorities.
Dates unknown:
The Hill Valley Telegraph published the photograph of Vice Principal Strickland smoking the cigar in his office. S.S. Strickland was suspended from the city council pending an investigation into the fire.
With Strickland off the council, Biff's mansion plans were approved.
Non-canon or disputable information ends here.
Hell Valley (also known as Biffhorrific 1985) timeline