The plane bringing home Corporal William Savage, Fusilier Samuel Flint and Private Robert Hetherington has just landed at RAF Brize Norton.
Close family will spend time with the coffins before the cortege passes through the village of Carterton where friends and family will pay their respects as a memorial bell tolls.
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Addressing veterans at an American Legion conference in Reno, Nevada, the president spoke in measured tones and stuck to prepared remarks.
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