grammatical number - Among his greatest hits (were?/was?) the anthem. Which verb is correct?

I read this article and found a sentence that says:

Among his greatest hits were the anthem "Bring Him Back Home," demanding Nelson Mandela's freedom from jail.

Could you explain why the sentence used 'were' as the verb? I think the subject and the object are inverted in this sentence. Therefore, it can say that

The anthem "Bring Him Back Home," demanding Nelson Mandela's freedom from jail was among his greatest hits.

So the subject is the anthem "Bring him back home" and I thought its verb should be 'was' because the anthem is in the singular.

I would appreciate a little bit of help.