The victorious soldiers marched back with their flags held high.

victorious 是形容词，由名词 victory（胜利）加上形容词后缀 -ious 构成，表示"胜利的、获胜的"。 soldiers 是 soldier 的复数形式，指"士兵、军人"。 victorious soldiers 指"获得胜利的士兵们"。