遠征【えんせい】
expedition, (military) campaign, tour (by a sports team, performer, etc.), visit
征服【せいふく】
conquest, subjugation, overcoming (a difficulty), conquering (e.g. a mountain), mastery (of a skill)
出征【しゅっせい】
going to war, departure for the front, departure for military service (in response to a draft)