Ralph and Jack run against each other because they both believe they should be the leader, this causes jelousy and anger towards Jack because Ralph won.
Build first, hunt later
Ralph wanted everybody to help build shelters and Jack is selfish and wants to have fun and hunt intead of building shelters which are necessary.
Piggy's glasses
Piggy's glasses are the only resource they have to create fire and this causes fights between groups and death.
Simons Death
Jack and his group kill piggy but clawing him and biting him to death.
Stealing
Jack and his group invade Ralphs camp and steal Piggy's glasses that way they have total control over fire. This causes more separation between the two and now Ralph's group wants them back.
Piggys crushing death
Roger pushes a boulder off the cliff and it collides with Piggy and kills him as he is pushed of the ledge by it. In this event the boulder also smashes the Conch shell into a ton of pieces.
