Stimulus “Every gun that is made, every warship launched, every rocket fired signifies, in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed.” President Dwight D. Eisenhower
Benefits of war: testing your national neighbor's capabilities, using up old depreciating resources, a fiscal policy of spending money that drives an economic boom, an outlet for aggressive members of society, a path to freedom for imprisoned criminals, a stronger in-group preference that increases national unity, history-making/war stories/honor/status generation, development of new technology, development of new social orders, signalling to other potential (ly more dangerous) enemies to stay away because your country is powerful, population control, a silver lining of developing modern-era buildings in more efficient/friendly neighborhood styles, investment into new infrastructure in the name of national security, reactionary "peace" movements/culture, etc.
You asked "Can good come from war."
If we interpret your question literally, the obvious answer is YES - it is possible to accomplish SOME good things through war. But that begs the question whether the end justifies the means. We can also ask whether there's a more sensible and/or ethical way to accomplish whatever good a war accomplishes.
For example, the American Civil War accomplished a very good thing: It freed the slaves.
However, some scholars have pointed out that the U.S. is the only country that used war as a solution to slavery; other countries abolished it peacefully. There were some other major problems with the Civil War and Abraham Lincoln both that can make one ask if the Civil War was a "good war," a "bad war" or something in between.
Thousands of years ago, various peoples fought to prevent other groups from encroaching on their lands and stealing their resources (primarily food and water). If we define these conflicts as war, then they might be viewed as necessary, rather than "good." If you didn't fight for your dinner, then you and your family would simply die.
Modern warfare, of course, is so very different, it's to hard to imagine a war that produces more good than bad.
Nevertheless, America's wars have produced lots of military clothing that people can often purchase at discount prices. Technically, that could qualify as a good thing, unless you balance it against the overall cost in blood and tax dollars.
War in a sense is life. But I doubt you are speaking of that. War is defense, but I don’t think you are speaking of that either. So in essence I think you are talking about war for the purpose of solving a difference of opinion, or, war for the purpose of forcing an ideology into another population. And what are the stakes? Freedoms? Resources? Globalization? Land? Economies? War is a multi-faceted idea.
As to the ethics of war I would say there is a duplicity in purpose. To ‘force’ anything in a sense is all that life is. Even the forceful injection of ideas and opinions through manipulations and propaganda is perhaps the war which endures daily.
So now I wonder if you are quoting Eisenhower to create some aspect of duplicity in saying the war of ‘psychology’ is moralistic compared to a ‘physical’ war. And ethically that is an opinion.
In history it can also be derived that war served as population control. And now, if that population control has shifted to a psychological control that, (for the sake of argument) kills the psychological losers and saves their opposite then what you have ended up with is a society that existed at the beginning of civilization, of hierarchy’s and inequalities in the same sense of ancient Egypt and Greece and Rome. Where slavery was instilled inside the society and may or may not have been labeled such at those times. And even if the law was instilled through fear and intimidation I am not sire it is all that different today.
Is war ethical? No, I don’t think so. I think what is ethical is solving problems through transparencies and then using intellect to understand the needs of people and the categories. creating a diversity which allows for the pursuits of happiness. And if the truth has to be hidden to make the world work then I think the world has evolved less than people think. I want to believe there exists a better equation that allows for expression and a better symbiosis with nature. Perhaps philosophy can find that equation.
The answer is an unequivocal 'yes'.
You didn't ask whether it's the best way, so discussions regarding alternatives are irrelevant.
Take the American Civil War as an example. In order to argue 'no' in this case, you have two options: 1) ending slavery is not good, or 2) the American Civil War did not end slavery. In my opinion, ending slavery was a good thing. As for item 2, history clearly records that the war ended slavery. If you hold that slavery in America was not good, your conclusion will be that war did something good in this case.
As a second example, consider the Jewish holocaust. Some people hold that 1) this never occurred, or 2) that extermination of the Jews was a good thing. It's possible that some argue that WW2 was not what ended the holocaust, but I have not heard this position. In my opinion, the holocaust occurred, and ending it was good (to say the least). Furthermore, I believe that the effort of the Allied forces is what brought about the end of the holocaust. Obviously, I then conclude that war accomplished something good.
If war means 'a state of armed conflict between different countries or different groups within a country', the answer is, 'No'. If it means defeating of the evils in people's mind, the answer is, 'Yes'. The epic Mahabharata and the Gita teach us that great lesson.
In wars there will certainly be great human loss on both sides. We can never ignore the sorrows and sufferings of the solders' and their family. Then what goodness can wars bring?
We may argue that the cause of the formation of the UN is World War/s. Well, now nobody can say that the UN is not for goodness. But when we say so, we don't remember the great efforts of great men in its formation. So we can't say that the UN is the effect/result of World War/s. It is actually the result of great efforts. When some nations suffered humiliating defeats, great changes happened to the Ego of some other nations also. If these changes had happened earlier, war wouldn't have become a necessity. So, I reiterate: As I mentioned earlier, "If war means defeating of the evils in people's mind", the answer is, 'YES, INDEED'. If there are good results, they are because some groups or nations practice their Dharma, NEVER BECAUSE OF WARS. It is terrific if people begin to replace the term 'practicing Dharma' by 'war.' There is a great chance of confusion if you can't discriminate the difference between war and Dharma. Good for one person may be bad for another person. "Good for whom?"--This is not specified in your question. So, to get a clear-cut answer, first you should clarify the term--'good'.
So, if you believe that a good result is because of wars, you can believe this also--'there must be another cause/s (great efforts) to make it a good result'...knowingly or unknowingly we ignore/forget them.
When thoughts become wild, for the sake of argument, one may say: "Wars can control population growth, Scavengers get plenty of food etc." But all these stuffs are against humanitarian values; I believe so. So, normally we cannot consider these stuffs as good things.