My German Shepherd 1 y.o. is so protective how can he be trained to not freak when a stranger comes.?

My suggestion would be to consult a trainer who knows what they are doing. Opinions on the internet from strangers, especially when dealing with a situation like this, can be very dangerous. There is nowhere near enough info in the question for anyone to give a suggestion on what to do.

The dog needs to be observed in the situations by someone who knows to find out exactly what the problem is. Many people mistake fear aggression for being "protective". There is a huge difference.

While the dog may simply need socialization, if you don't know what you are doing, you can make it worse. More.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.