Jack and Ralph accidentally let the fire go out while using the glasses to start it. Their neglect in keeping the fire going led to a missed opportunity for rescue when a ship passed by the island.
Fire and more importantly Piggy's Glasses.
There is no attack by Jack's tribe on Ralph and his followers. Jack led a night-time raiding party, comprising of himself, Roger and Maurice, to steal Piggy's glasses in chapter 10: The Shell and the Glasses.
Ralph doesn't tell Jack about the glasses as Jack already knows about them, mainly because he stole them. Ralph pointed out that Jack could have had fire at any time if he'd simply asked for it but instead he'd come sneaking up like a thief and stole Piggy's glasses. Jack demanded that he repeat the accusation and when Ralph obliged Jack rushed forward and stabbed his spear at Ralph's chest. Ralph managed to block the thrust with his own spear and then swung it around to land a stinging blow to Jack's ear.
Ralph opposes Jack's violent ways. He also trying to stop the boys approaching Jack's view of the boys. Moreover, by hunting Ralph, Jack is trying to show who the real leader is and why everyone should follow him.
"In this chapter, Piggy's glasses are stolen by Jack . The Glasses are of great importance since it is only by them that fire can be created. At first , Ralph and Samneric think that Jack's raiding party came for the Conch but in reality , they came for the Glasses."
Jack's group steals Piggy's glasses and the conch shell from Ralph's group in the novel "Lord of the Flies." These items represent order, intellect, and democracy, which are valued by Ralph's group but rejected by Jack's group in their descent into savagery.
Well in chapter 10 Jack and his tribe of savages invade Ralph's tribe (made of up Ralph, Sam and Eric, Piggy, and one/two littluns) in order to steal Piggy's glasses, which is overall the power to start a fire on the island. Jack might have mentioned this plan in chapter 9 so I'm hoping this is the right answer to your question.
In chapter 10: the Shell and the Glasses Jack selected Roger and Maurice to accompany him on his raid to 'get fire' from Ralph's group, in fact they stole Piggy's glasses
piggy's glasses
The is one over riding reason why Piggy asks for his glasses back, he can barely see without them. As he said earlier when he rehearsed what he would say with Ralph and the twins, "I won't ask for my glasses back as a favour. I won't ask Jack to be a sport, I'll say not because he's strong but because what's right's right."
Roger and Maurice are the ones that attack Jack and Piggy because Jack wants Piggy's glasses.
Ralph takes a makeshift spear to use as a weapon against Jack in "Lord of the Flies." He repurposes a stick, sharpens one end, and uses it to defend himself and confront Jack's tribe.