What were Ralph's internal and external conflicts?
Ralph is an absolutely fantastic character to read about, and a large part of that has to do with the fact that he struggles both internally and externally. I would say that he has two main external struggles. The first struggle is fairly obvious based on the book's setting. It is a man vs. nature conflict. He is stranded on a deserted island; therefore, he has to fight against hunger, thirst, exposure, injury, etc. The island isn't a tropical paradise that delivers food from heaven each morning. He and the boys have to hunt down food and work together to build shelter that protects them from the elements. The second major external conflict for Ralph is a man vs. man conflict. Starting right from Chapter 1, Ralph and Jack are butting heads. Both boys think they should be the one to lead, and this conflict escalates little by little each chapter until Jack is outright trying to kill Ralph.
Internally, Ralph struggles with how to lead. He wants to be "cool" and fair, but he also has a good handle on what needs to be done. He knows that some jobs aren't going to be glorious, but they have to be done all the same. He struggles with exactly what kind of leader he wants to be and what kind of leader he needs to be.
Ralph is one of the most complex characters in this novel. Internally, he struggles between his accepted leadership and his actual age. As the elected leader, he feels the responsibility of both keeping them together as a civilized society (hence his attempt at shelters, bathrooms, etc.) and of getting them rescued (his obsession with the fire). However, as a kid, he envies the other boys, Jack especially, because of their ability and willingness to shun responsibility and just have fun. This is seen most pointedly during his argument on the mountain with Jack after they missed their chance to be saved the first time.
Ralph's external battles are mostly related to that same idea. He fights (physically, mentally, and emotionally) with Jack about what the boys should be doing. He recognizes Piggy as an outsider and pokes of him for that. He also must defend his actions against all of Jack's tribe once they abandon reason. Ralph has some obvious conflict with the elements of nature, also, but their importance pales in comparison to his relationships with the other characters.
The end of the novel also highlights Ralph's confusion about society itself. He struggles to reconcile what he knows of school - the rules, the structure, the discipline - with what he knows of the world - violence and war. Although uncomforable with Jack's violent treatment of some of the boys, Ralph hesitates to contradict him because it appears normal to him. It is when the naval officer stumbles upon him and comments on the "play" of the boys that Ralph understands society. He weeps then for the "end of innocence" and the "darkness in men's heart". He realizes that the discipline of society is barely covering up its true, violent nature.