Original sentence: Many groups call themselves anti-war activists though their opinions may be different: some anti-war activists may be equally opposed to both sides' military campaign; in contrast, many modern activists are against only one side's (usually the most powerful) campaigns
Edited sentence: Many groups call themselves anti-war activists though their opinions may be different: some anti-war activists may be equally opposed to both sides' military campaign; in contrast, many modern activists are against only one side's (usually the most powerful) campaigns, feeling that the war will end if one side pulls out, as with the Second Iraq War