The 'war' group
These nouns are used to indicate that two or more people, groups, or things are in opposition to each other. These are reciprocal nouns; they are sometimes followed by a prepositional phrase beginning with with.
at cross-purposes (with ...) at loggerheads (with ...) at odds (with ...) at variance (with ...) at war (with ...)
When Reagan was in the White House, few minded that so many of his statements were at variance with the facts.
England was at war.