This question is directly related to my last: What would be the impact of a modern programmer and laptop being dropped into World War II, possibly breaking Enigma? Where a young programer, and laptop. is somehow accidentally sent back to early WW2 time.
The problem is that the protagonist is a quasi-pacifist (not oppose to all war, willing to agree that WW2 probably has to happen now that Hitler is in power, but still is very uneasy supporting the war). He would rather focus on progressing science, quality of life, and pushing the government towards more progressive/modern policies, particularly in terms of civil rights and treatment of others.
He will get attention for himself by mentioning he could break Enigma with little effort, drawing the attention of the military. However, he tries hard to push towards using the laptop for non-military proposes, or trading it's military use for some other positive policy being enacted. For instance I'm almost certain he would try to exchange the ability to do code breaking for minimizing or stopping the Japanese Internment camps that he sees as a shameful black mark on US history. The question is could he make 'trades' like this?
This involves a few questions. First, how does he keep the government from just taking his computer and tossing him out when he becomes a nuisance? He will claim to have placed hooks in the OS, so that if he doesn't get occasional unsupervised access to 'defuse' them the computer it will lock itself or wipe the harddrive. The truth is he doesn't know how to do this, it's a bluff to try to discourage the laptop being taken away from him.
He's also the only programmer they have. The loss of his programing and computer expertise would greatly limit the usefulness of the laptop, though they could eventually figure out how to write code on it themselves. The government could try to bully him into writing code, but he has pointed out it's quit easy for him to lie about what can or can't be done, work at a slow down, provide false results, or just run an application that fries the computer by overclocking it, having someone doing such important work uncooperative is dangerous.
How much bargaining power could he reasonably have in a situation like this? Could anyone make as massive a promise as to cut back or stop the Japaneses internment camps, or is the government simply too big for any party to be able to follow through with something like that? What bargaining chips could someone high up in the government who is desperate for his support of the war effort offer that they could actually gaurentee? How far could someone like our time traveler push before the government of WW2 era would likely stop bargaining and start strong arming?
Keep in mind he would likely mildly alienate those involved in the war effort with his different world views. He is offended and tries hard to argue against the racist cartoons/propaganda against jap and German people, which, combined with his more pacifist view to the war effort, would make some see him as an enemy sympathizer, or perhaps just foolishly naive. Culture clash over other topics, like civil rights, smoking, and sex/sexuality, could also occur.
He also has to deal with the fact that anyone who hasn't seen his laptop in action will never believe he is a time traveler, and even those that have often suspect he got it from some group with advanced technology as being more believable then time travel. He may try "the future will look back and be ashamed of this action", but not everyone will believe that's true.
In this scenario the programer has very limited interest or knowledge of History in general, and particularly knows very little of the war due to his pacifist nature causing him to avoid listening to or learning about war history. What history he does know is more of a cause->effect concept, but he can never remember dates or time frames. As such he has limited historical knowledge which could be of any use directly in the war effort. He knows D-day, pearl harbor, and maybe midway happened, but not when, and not too much about how. He knows more about non-war history, particularly history of science and computers, but still nothing too specialized. I may have him be more aware/interested in internet and history of it's development, as something he may to try to push them towards developing sooner.
He fell through time while walking to college, and as such has with him his backpack and school supplies. This includes his laptop, one Graphing Calculator, and a cheap smart phone who's battery ran out very shortly after arriving. The Graphing calculator is in some ways more useful then the laptop, because it's much easier to teach scientists how to use it without having to go through him, but at the same time that also makes it much harder to keep the government from just taking it and using it without his permission.
His backpack could also have 1-2 textbooks, of whatever subject I decide it's reasonable and interesting for him to have. The books will not include "history of WW2" or anything too 'game breaking', but I'm keeping open the possibility of having a book which is somewhat relevant if it makes the story interesting. Computer Networking, some civil rights-related course, and basket weaving 101 are all possible textbook topics :)