Complete the following sentence: During the Vietnam war, Walton served in the Green Berets as part of the Studies and Observations Group. <unk> <unk> <unk>
<unk> <unk> <unk> <unk> Walton<unk>later<unk>received<unk> a<unk>Silver<unk>Star<unk>for<unk>bravery<unk>in<unk> combat.