It depends on context. If it's in England, the butter dish was made before the English Civil War - Wikipedia, the free encyclopedia ; it's probably made of silver; I expect pre-civil war butter dishes are very rare, because supporters of the royalist cause contributed all their family silver to the war effort. But I'm not an expert in silverware!
Alternatively, the butter dish was made before the American Civil War - Wikipedia, the free encyclopedia . I have a feeling that anything made before that war is called 'ante bellum' - which is Latin for 'pre-war'! So I'd guess my first guess was right.