OP hasn't just whacked up a fence, from his first post they have said they've tried to have a conversation with the neighbours which resulted in them telling the OP that they'll destroy it if he puts it up.
I would have no interest in speaking with neighbours like that a second time round when all they had retorted with is threat.
Compromise goes both ways.
From what he has said he hasn't offered any compromise, all he has done is try to convince them that a 6ft fence is in their best interests, they clearly disagree. That is not compromise, that is enforcement of will.
From what he has said it appears to be his way or nothing, I was only suggesting that a 6ft solid fence is not the only option if it is privacy he requires. There are other options that would give him his privacy without removing he light from the neighbours garden.