War with the exception of brigandage is an act of politics and an instrument of policy. As such to wage war is to exercise both statesmanship and generalship. Although in recent history the conduct of war is seperated between the government and the general staff, I should think that in the Third Age, the two bodies were one and their processes were carried out in unity.
When Aragon II as Thorongil devised, planned and led the military campaigns of Gondor, he was charting the foreign policy of his people and in essence waging a war of Dúnedain civilization against other civilizations to ensure the the interests and security of his people were upheld.
There is very little detail written on his generalship and we do not know if he was granted plenipotentiary in his conduct with other civilizations. But we do know that at the end of Thorongil's service, the Kingdom was surrounded by a litter of broken and weakened states that would not threaten her for years to come. If it was Aragon II's intention to prolong the survival of Gondor, then he had succeeded.
I would also submit that even greater than his military exploits, was his one single act just as Gondor achieved regionally superiority - his abrupt departure, his
coup de maître
Without Aragon II as its guiding light, Gondor lost its sense of bearing and failed to achieve regionally hegemony. This was what I believe Aragon II intended for Gondor; to be a giant at peace with its neighbours and not embark on a Machiavellian path of unchecked expansionism. And indeed the only way to do so was to provide an obstacle to expansion and that was the absence of his services. Aragon II must have gambled on the fact that without Thorongil the Great,
no one in Gondor, not even Denethor II would dare fill his shoes and he was absolutely right.
Expansionism always carried its share of risks. Aragon II would have calculated that after his campaigns, Gondor was exhausted and any expansion would be over-expansion, leaving the enlarged state less competent and more vulnerable externally and internally. He must have also been astute enough to realize that should the surrounding weaker states percieve the eminent threat Gondor posed, they would have consolidated and formed an alliance, resulting in a nightmare scenario of his Kingdom surrounded by a sea of united hostile states.
And lastly I think Aragon II left the adjacent civilizations weakened but unmolested for very humane reasons. He was Dúnedain by blood but the genius in him must have understood the roots of diversity and the celebration of universal brotherhood. Instead of having Gondor conquer all and impose its set of cultures, traditions and values to the conquered people resulting in the lost of their indigenous counterparts, Aragon chose to preserve them for future prosperity. He must have thought that future relations could be built upon shared common interests and values than on blood and iron.
That last attribute could well be the reason that even after the Third Age, Aragon II carried out new expeditions, even beyond the sea of Khun. Perhaps like a well-known real-life colossal who left his mark on this world millennias ago, Aragon II wanted to create a greater empire of universal brotherhood where the high blood of the Dúnedain was irrelevant and where the shared visions of a united race of men were supreme.
Illuvatar would have applauded!
