What specific moment incites the central conflict of The Chocolate War?
Well, on a biographical level, the entire plot/conflict is sparked by the author's son's decision not to sell chocolates for his school. However, if you mean within the novel itself, it is similar; everything unfolds from Jerry deciding not to sell the chocolates. This happens in Chapter 13. There are more violent conflicts, such as the brutal final fight, but they all start from this.