John Stuart Mill! 

War is an ugly thing, but not the ugliest of things: the decayed and
degraded state of moral and patriotic feeling which thinks nothing is
worth a war, is much worse. When a people are used as mere human
instruments for firing cannon or thrusting bayonets, in the service
and for the selfish purposes of a master, such war degrades a people.
A war to protect other human beings against tyrannical injustice; a
war to give victory to their own ideas of right and good, and which is
their own war, carried on for an honest purpose by their free
choice,—is often the means of their regeneration. A man who has
nothing for which he is willing to fight, nothing which is more
important than his personal safety, is a miserable creature who has no
chance of being free, unless made and kept so by the exertions of
better men than himself. As long as justice and injustice have not
terminated their ever-renewing fight for ascendancy in the affairs of
mankind, human beings must be willing, when need is, to do battle for
the one against the other.