Accepting an award for the work of his and Prince William's foundation, he told an audience in Washington: "They have paid a terrible price to keep us safe and free."
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"The very least we owe them is to make sure that they and their brave families have everything they need through their darkest days.
"For these selfless people, it is after the guns have fallen silent, the din of battle quietened, that the real fight begins."
VIP guests at the black tie gala included UN Secretary General Ban ki-Moon, General Colin Powell, and a host of US senators and congressmen.
General Powell, one of the most respected Army and political leaders of his generation, paid tribute to the royal, saying he preferred to refer to him by his military title, Captain Wales.
"He is a young man, who has grown up with good looks and royal privileges. It would have been easy for him to choose a life of ease and leisure.
"Instead he chose a more difficult path and by so doing he has become an example to millions of others."
Warming to his theme, the politician also quipped that the royal had attracted the attention of a new demographic to the cause.
"We have a record number of young, single women attending this year!" he joked.
It was a rare moment of comic relief during a ceremony which was largely a sombre and serious affair.
As someone who has served on the front line in Afghanistan, raising awareness for the war wounded is a cause close to Harry's heart.
In 2011, he joined a group of disabled servicemen on an arctic expedition.
The trip was in aid of charity Walking With The Wounded of which the prince is patron.
The group were forced to abandon an attempt to climb Mount Everest because of safety fears on Monday.
The charity said unseasonably warm weather had increased the risk of avalanches.
Harry told of their frustrated attempt as he collected his award. Despite the setback, he said: "The mere fact that they are up there on that fearsome peak, I find totally amazing."