Is aggressive war of territorial expansion good?

Is aggressive war of territorial expansion good? Such war is found throughout history, and those who waged it must have seen it as good. What was their thinking?

Arguments for

 * All great empires such as Egypt, Ancient Greece, Ancient Rome and the United States were based on an aggressive war of territorial expansion. It cannot be all bad, or else we would not have the goods that great empires produce.
 * Countries can expand without war, e.g. by marriage between rulers. European Union was created as a voluntary union of countries. An aggressive war does not seem necessary to create larger political units that can achieve good things.
 * That assumes that the goods created by empires are more important than moral concerns.
 * The great Ancient Greek and Roman philosophy, law and science are more important than a loss of life of some individual humans, who are born and die in thousands and are fundamentally replaceable.
 * Nothing like that is remotely acceptable. Intentionally killing an innocent person for a larger aim, perhaps developing a useful medicine, is not good and not acceptable.
 * That's a matter of a fundamental assumption about good. Humanists claim to treat each human as very valuable, whereas the above objected argument claims and assumes that great achievements are more valuable than individual humans and that it is good to maximize value on the whole.
 * Not sure what to say about this fundamentally immoral assumption.
 * If we accept that a larger good justifies mass murder, then a larger good justifies a single murder. That is not remotely acceptable and makes no sense.
 * A killing in the context of war is not murder. The notion of murder requires a civilian (extra-war) context.
 * If it is not notionally murder, it is not any less morally wrong than murder.
 * The question was not whether it was morally right or wrong but rather whether it was good.
 * The argument seems to assume that it is sometimes good to do something that is morally wrong.
 * That seems like hair-splitting semantics around the words good, value, right, morally right, bad, morally wrong, and the like. There may be some value in keeping these notions distinct, but it complicates the discussion and removes the fundamental disagreement from discussion: is it acceptable to intentionally kill someone innocent for a larger aim?
 * But the intention does not need to be the death of the particular person but rather the creation of an empire. If the target nation willingly subjugates, they will be spared. They should understand that empires are good. If they were asked to subjugate themselves in no unequivocal terms and yet they resist, then they are a partial cause of their own death, under causal analysis.
 * Devious.
 * Then it would be more productive to ask whether it was acceptable, just, justified or the like. The point is that a creation of a great empire is good overall, and that the good created is larger than the good lost.
 * The above seems to be a particular odious worldview that is going to be hard to refute using just means of logical, semantic and factual analysis.
 * Expanding on the above, a large empire created by territorial expansion creates a condition of peace, eventually saving human lives that would otherwise be lost in wars that the political units would fight anyway.
 * There could be an "alliance of princes" to create a lasting peace on Earth. The result would not be an empire but rather a defensive alliance of political units for mutual protection. The same political units could create other kinds of alliance, perhaps unify on units of measure. And this is what happened: many countries have adopted the metric system without force, countries have joined forces to create an economic union, the European union, and countries created a defensive alliance, NATO, without being forced to do so. Countries have signed a range of international agreements without being forced to do so.
 * Countries could have been forced economically to sign these agreements.
 * Being "forced" economically and militarily makes all the moral difference.
 * It is rather more probable that countries adopted the metric system since they saw merit in it.
 * Not joining European Union is economically viable, as exemplified by Switzerland. Thus, there was no economic compulsion either. It was a relatively free decision in expectation of economic benefits, but not out of sheer necessity.
 * A lasting peace on Earth would create decay. A country that does not need to fight wars for existence or expansion becomes decadent and spoiled.
 * If the objective is to create a challenge to prevent decay, there is plenty of it in sports, science and the arts, with no need to violate fundamental human rights.
 * These kinds of challenges are nowhere near to the level of war.
 * It is the threat of war that drives military expenditures and the associated scientific and technological progress. It was shown clearly in the competition between the Unites States and the Soviet Union.
 * It is not obvious that similar kinds of expenditures could not be created for peaceful purposes.
 * Human species probably originated via Darwinian evolution by natural selection, by incrementally enhancing biological innate capabilities to wage aggressive wars of one tribe against another. This would be especially so in so far as waging a war requires a brain capacity. Thus, it was via a competition within species that homo sapiens with its brain originated. The method of origination of that which we cherish, humankind, cannot be all bad.
 * That seems to be an error of a failed is-ought distinction or a naturalistic fallacy.
 * The method of origination may well be bad if it is all too likely to lead to humanity's demise or decline; see arguments against. It could have been good for origination, but we may still recognize it as bad, to be abandoned.
 * That may mean that the brain capacity that we all so cherish may be not so good and morally unobjectionable as we think. At least, a great intelligence in combination with bad intent is something we do not cherish.
 * The same process of origination resulted in the creation of the innate moral sense that tells us that an aggressive war is morally bad. Instead of pondering the origination process, we should use our moral sense.
 * Given the humanity's clear capacity for great evil, to assume that a process that has created that capacity is automatically good with all its aspects seems unjustified.
 * War is a manifestation of conflict, which is one of the foundational principles of the world. Without conflict, everything would be just uniform undifferentiated mass. In general, forms replace other forms, biological forms compete with other forms for existence and prevalence in the empirical world. That which is the basis of all that is cannot be bad.
 * The above confuses the notions of war, conflict, contrast and difference. When a T-shirt has blue and yellow stripes, there is a difference and contrast between the colors, but no conflict and no war. When one portion of a vessel has hot water and another has cold water, there is no conflict between the two portions.
 * Eliminating human war does not eliminate all conflict, contrast and competition in the world. There is still hot and cold and day and night; there is a human competition in sports and a debate and a conflict in the court of law. Whatever happens between plants and animals is unaffected by elimination of war.

Arguments against

 * An aggressive war of territorial expansion is like a mass murder. Innocent civilians die including women and children and innocent soldiers die, their only guilt being a defense of their country. A single murder is not acceptable and mass murder or its analog even less so.
 * They do not need to die if they subjugate themselves to the empire without fight.
 * By that logic, it is good if the somewhat weaker subjugate themselves to the will of the stronger.
 * That is a law of nature.
 * Whether something is good or not is not a law of nature, like a physical law. What is a law of nature is that when the weaker do not subjugate themselves to the stronger and fight back, many of them die, yet they sometimes succeed in defending themselves.
 * An aggressive war of territorial expansion destroys cultural heritage, e.g. ancient buildings.
 * The acceptance of an aggressive war of territorial expansion as a good creates conditions for the ultimate destruction of humanity or at least civilization. Since, countries aiming to wage war must keep investing in military technology to outdo the other countries, resulting in arms race. The arms race can eventually result in creation of the ultimately destructive weapon. When that weapon is developed, it is only a matter of time, short on the geological time scale, that the weapon is going to be used, possibly by error. And this is what happened short of the weaponry being used to destroy civilization. It was not a priori certain to happen since it was not clear the technological potential for such a weapon was there, but it was in fact there. All this can be prevented if countries create defensive alliances and if they agree to reduce creation and stocking of particularly destructive weapons. And this is what in part happened.
 * A modern aggressive war of territorial expansion can destroy natural environment via use of nuclear weapons.
 * That argument would not apply to ancient aggressive wars.
 * A modern aggressive war of territorial expansion can make a large area uninhabitable if fighting hits a nuclear power plant badly enough.
 * That argument would not apply to ancient aggressive wars.